2178720045657 has 24 divisors (see below), whose sum is σ = 3183210969120. Its totient is φ = 1435794085440.

The previous prime is 2178720045631. The next prime is 2178720045727. The reversal of 2178720045657 is 7565400278712.

2178720045657 is a `hidden beast` number, since 2 + 1 + 7 + 8 + 72 + 0 + 0 + 4 + 565 + 7 = 666.

It is not a de Polignac number, because 2178720045657 - 2⁸ = 2178720045401 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2178720045157) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2816982 + ... + 3506112.

It is an arithmetic number, because the mean of its divisors is an integer number (132633790380).

Almost surely, 2^{2178720045657} is an apocalyptic number.

It is an amenable number.

2178720045657 is a deficient number, since it is larger than the sum of its proper divisors (1004490923463).

2178720045657 is a wasteful number, since it uses less digits than its factorization.

2178720045657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 693173 (or 693170 counting only the distinct ones).

The product of its (nonzero) digits is 6585600, while the sum is 54.

The spelling of 2178720045657 in words is "two trillion, one hundred seventy-eight billion, seven hundred twenty million, forty-five thousand, six hundred fifty-seven".