640662156 has 24 divisors (see below), whose sum is σ = 1660976240. Its totient is φ = 213554016.

The previous prime is 640662137. The next prime is 640662161. The reversal of 640662156 is 651266046.

It is a happy number.

640662156 is a `hidden beast` number, since 640 + 6 + 6 + 2 + 1 + 5 + 6 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 640662156.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2965921 + ... + 2966136.

Almost surely, 2^640662156 is an apocalyptic number.

It is an amenable number.

640662156 is an abundant number, since it is smaller than the sum of its proper divisors (1020314084).

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

640662156 is a wasteful number, since it uses less digits than its factorization.

640662156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5932070 (or 5932062 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 640662156 is about 25311.3049051210. The cubic root of 640662156 is about 862.0709760447.

The spelling of 640662156 in words is "six hundred forty million, six hundred sixty-two thousand, one hundred fifty-six".