640256521356 has 72 divisors (see below), whose sum is σ = 1658126023008. Its totient is φ = 208185120000.

The previous prime is 640256521337. The next prime is 640256521393. The reversal of 640256521356 is 653125652046.

640256521356 is a `hidden beast` number, since 6 + 40 + 2 + 56 + 521 + 35 + 6 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12640281 + ... + 12690831.

Almost surely, 2^640256521356 is an apocalyptic number.

It is an amenable number.

640256521356 is an abundant number, since it is smaller than the sum of its proper divisors (1017869501652).

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

640256521356 is a wasteful number, since it uses less digits than its factorization.

640256521356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59183 (or 59178 counting only the distinct ones).

The product of its (nonzero) digits is 1296000, while the sum is 45.

The spelling of 640256521356 in words is "six hundred forty billion, two hundred fifty-six million, five hundred twenty-one thousand, three hundred fifty-six".