231187129015921 has 9 divisors (see below), whose sum is σ = 250338939539979. Its totient is φ = 213403321248936.

The previous prime is 231187129015837. The next prime is 231187129015957. The reversal of 231187129015921 is 129510921781132.

It is a happy number.

The square root of 231187129015921 is 15204839.

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

It can be written as a sum of positive squares in only one way, i.e., 34199279440225 + 196987849575696 = 5848015^2 + 14035236^2 .

It is not a de Polignac number, because 231187129015921 - 2⁷ = 231187129015793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (231187129015121) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 197078106 + ... + 198247708.

Almost surely, 2^{231187129015921} is an apocalyptic number.

231187129015921 is the 15204839-th square number.

231187129015921 is the 7602420-th centered octagonal number.

It is an amenable number.

231187129015921 is a deficient number, since it is larger than the sum of its proper divisors (19151810524058).

231187129015921 is an frugal number, since it uses more digits than its factorization.

231187129015921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2339232 (or 1169616 counting only the distinct ones).

The product of its (nonzero) digits is 544320, while the sum is 52.

The spelling of 231187129015921 in words is "two hundred thirty-one trillion, one hundred eighty-seven billion, one hundred twenty-nine million, fifteen thousand, nine hundred twenty-one".