640265643402 has 256 divisors, whose sum is σ = 1781154385920. Its totient is φ = 148135219200.

The previous prime is 640265643389. The next prime is 640265643427. The reversal of 640265643402 is 204346562046.

It is a super-2 number, since 2×640265643402² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 244281652 + ... + 244284272.

It is an arithmetic number, because the mean of its divisors is an integer number (6957634320).

Almost surely, 2^640265643402 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640265643402, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (890577192960).

640265643402 is an abundant number, since it is smaller than the sum of its proper divisors (1140888742518).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640265643402 is a wasteful number, since it uses less digits than its factorization.

640265643402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4317.

The product of its (nonzero) digits is 829440, while the sum is 42.

The spelling of 640265643402 in words is "six hundred forty billion, two hundred sixty-five million, six hundred forty-three thousand, four hundred two".