2156909831920 has 40 divisors (see below), whose sum is σ = 5014888352496. Its totient is φ = 862751374848.

The previous prime is 2156909831891. The next prime is 2156909831927. The reversal of 2156909831920 is 291389096512.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2156909831927) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6951619 + ... + 7255261.

Almost surely, 2^{2156909831920} is an apocalyptic number.

2156909831920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2156909831920 is an abundant number, since it is smaller than the sum of its proper divisors (2857978520576).

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

2156909831920 is a wasteful number, since it uses less digits than its factorization.

2156909831920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 392449 (or 392443 counting only the distinct ones).

The product of its (nonzero) digits is 2099520, while the sum is 55.

The spelling of 2156909831920 in words is "two trillion, one hundred fifty-six billion, nine hundred nine million, eight hundred thirty-one thousand, nine hundred twenty".