2157172155 has 80 divisors (see below), whose sum is σ = 3990549024. Its totient is φ = 1114145280.

The previous prime is 2157172123. The next prime is 2157172159. The reversal of 2157172155 is 5512717512.

2157172155 is a `hidden beast` number, since 2 + 1 + 571 + 72 + 15 + 5 = 666.

2157172155 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 2157172155 - 2⁵ = 2157172123 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2157172159) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 2706217 + ... + 2707013.

Almost surely, 2^2157172155 is an apocalyptic number.

2157172155 is a deficient number, since it is larger than the sum of its proper divisors (1833376869).

2157172155 is a wasteful number, since it uses less digits than its factorization.

2157172155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1018 (or 1009 counting only the distinct ones).

The product of its digits is 24500, while the sum is 36.

The square root of 2157172155 is about 46445.3674223813. The cubic root of 2157172155 is about 1292.0964558707.

Adding to 2157172155 its reverse (5512717512), we get a palindrome (7669889667).

The spelling of 2157172155 in words is "two billion, one hundred fifty-seven million, one hundred seventy-two thousand, one hundred fifty-five".