2156230864921 has 27 divisors (see below), whose sum is σ = 2537844736989. Its totient is φ = 1826656294848.

The previous prime is 2156230864919. The next prime is 2156230864961. The reversal of 2156230864921 is 1294680326512.

The square root of 2156230864921 is 1468411.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 845581398025 + 1310649466896 = 919555^2 + 1144836^2 .

It is not a de Polignac number, because 2156230864921 - 2¹ = 2156230864919 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2156230864901) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 914818875 + ... + 914821231.

Almost surely, 2^{2156230864921} is an apocalyptic number.

2156230864921 is the 1468411-st square number.

2156230864921 is the 734206-th centered octagonal number.

It is an amenable number.

2156230864921 is a deficient number, since it is larger than the sum of its proper divisors (381613872068).

2156230864921 is an frugal number, since it uses more digits than its factorization.

2156230864921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4906 (or 2453 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 49.

Multiplying 2156230864921 by its sum of digits (49), we get a square (105655312381129 = 10278877²).

2156230864921 divided by its sum of digits (49) gives a square (44004711529 = 209773²).

The spelling of 2156230864921 in words is "two trillion, one hundred fifty-six billion, two hundred thirty million, eight hundred sixty-four thousand, nine hundred twenty-one".