72157640 has 32 divisors (see below), whose sum is σ = 164187000. Its totient is φ = 28537344.

The previous prime is 72157637. The next prime is 72157651. The reversal of 72157640 is 4675127.

It can be written as a sum of positive squares in 4 ways, for example, as 56460196 + 15697444 = 7514^2 + 3962^2 .

It is a junction number, because it is equal to n+sod(n) for n = 72157597 and 72157606.

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, 6575 + ... + 13694.

Almost surely, 2^72157640 is an apocalyptic number.

It is an amenable number.

72157640 is an abundant number, since it is smaller than the sum of its proper divisors (92029360).

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

72157640 is a wasteful number, since it uses less digits than its factorization.

72157640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20369 (or 20365 counting only the distinct ones).

The product of its (nonzero) digits is 11760, while the sum is 32.

The square root of 72157640 is about 8494.5653214276. The cubic root of 72157640 is about 416.3201584947.

The spelling of 72157640 in words is "seventy-two million, one hundred fifty-seven thousand, six hundred forty".