2156431644 has 18 divisors (see below), whose sum is σ = 5450980080. Its totient is φ = 718810536.

The previous prime is 2156431643. The next prime is 2156431661. The reversal of 2156431644 is 4461346512.

2156431644 is a `hidden beast` number, since 2 + 1 + 5 + 6 + 4 + 3 + 1 + 644 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 59900879 = 2156431644 / (2 + 1 + 5 + 6 + 4 + 3 + 1 + 6 + 4 + 4).

It is a junction number, because it is equal to n+sod(n) for n = 2156431599 and 2156431608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2156431643) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 29950404 + ... + 29950475.

Almost surely, 2^2156431644 is an apocalyptic number.

It is an amenable number.

2156431644 is an abundant number, since it is smaller than the sum of its proper divisors (3294548436).

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

2156431644 is a wasteful number, since it uses less digits than its factorization.

2156431644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59900889 (or 59900884 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

The square root of 2156431644 is about 46437.3948881718. The cubic root of 2156431644 is about 1291.9485892696.

The spelling of 2156431644 in words is "two billion, one hundred fifty-six million, four hundred thirty-one thousand, six hundred forty-four".