2156173812 has 72 divisors (see below), whose sum is σ = 5930220296. Its totient is φ = 656584704.

The previous prime is 2156173793. The next prime is 2156173841. The reversal of 2156173812 is 2183716512.

2156173812 is a `hidden beast` number, since 2 + 1 + 5 + 617 + 38 + 1 + 2 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 376515216 + 1779658596 = 19404^2 + 42186^2 .

It is a super-2 number, since 2×2156173812² = 9298171015109222688, which contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21648 + ... + 69144.

Almost surely, 2^2156173812 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2156173812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2965110148).

2156173812 is an abundant number, since it is smaller than the sum of its proper divisors (3774046484).

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

2156173812 is a wasteful number, since it uses less digits than its factorization.

2156173812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47617 (or 47612 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 2156173812 is about 46434.6186804630. The cubic root of 2156173812 is about 1291.8970969557.

The spelling of 2156173812 in words is "two billion, one hundred fifty-six million, one hundred seventy-three thousand, eight hundred twelve".