2151561231 has 16 divisors (see below), whose sum is σ = 3290321920. Its totient is φ = 1388103480.

The previous prime is 2151561227. The next prime is 2151561233. The reversal of 2151561231 is 1321651512.

2151561231 is a `hidden beast` number, since 2 + 1 + 5 + 15 + 612 + 31 = 666.

It is not a de Polignac number, because 2151561231 - 2² = 2151561227 is a prime.

It is a super-2 number, since 2×2151561231² = 9258431461484470722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2151561195 and 2151561204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2151561233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1284445 + ... + 1286118.

It is an arithmetic number, because the mean of its divisors is an integer number (205645120).

Almost surely, 2^2151561231 is an apocalyptic number.

2151561231 is a deficient number, since it is larger than the sum of its proper divisors (1138760689).

2151561231 is a wasteful number, since it uses less digits than its factorization.

2151561231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2570603 (or 2570597 counting only the distinct ones).

The product of its digits is 1800, while the sum is 27.

The square root of 2151561231 is about 46384.9246091874. The cubic root of 2151561231 is about 1290.9752117372.

The spelling of 2151561231 in words is "two billion, one hundred fifty-one million, five hundred sixty-one thousand, two hundred thirty-one".