PHP 5.3 suppots 64 bit numbers

The PHP 5.3 supports processing 64 bit data for the integer values only, but the floating point numbers remains constant as follows
Double => The value stored as per IEEE 754 standard

32 bit Platform

Integer => can hold 32 bit values => 2 ^31 to 2^31-1 => 2147483648 to 2147483647
Float => can hold 64 bit values => Mantissa(m):0-51,Exponent (e):52-62,Sign:1, =>4.9 x 10-307 .. 1.8 x 10+308

64 bit Platform

Integer => can hold 64 bit values =>2 ^63 to 2^63-1 => 9223372036854775808 to 9223372036854775807
Float => can hold 64 bit values => Mantissa(m):0-51,Exponent (e):52-62,Sign:1, =>4.9 x 10-307 .. 1.8 x 10+308

because it is hardware dependent, All the 64 version of hardware like AMD64 , IA64 supports 64 bit integers
AMD64 =>Athlon64, Quad Code , Core2Duo
IA64=> only for Itanium processor family