231289921 has 2 divisors, whose sum is σ = 231289922. Its totient is φ = 231289920.

The previous prime is 231289859. The next prime is 231289931. The reversal of 231289921 is 129982132.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 152275600 + 79014321 = 12340^2 + 8889^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-231289921 is a prime.

It is not a weakly prime, because it can be changed into another prime (231289931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115644960 + 115644961.

It is an arithmetic number, because the mean of its divisors is an integer number (115644961).

Almost surely, 2^231289921 is an apocalyptic number.

It is an amenable number.

231289921 is a deficient number, since it is larger than the sum of its proper divisors (1).

231289921 is an equidigital number, since it uses as much as digits as its factorization.

231289921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 37.

The square root of 231289921 is about 15208.2188634961. The cubic root of 231289921 is about 613.8358314678.

The spelling of 231289921 in words is "two hundred thirty-one million, two hundred eighty-nine thousand, nine hundred twenty-one".