231751921 has 2 divisors, whose sum is σ = 231751922. Its totient is φ = 231751920.

The previous prime is 231751901. The next prime is 231751943. The reversal of 231751921 is 129157132.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 125888400 + 105863521 = 11220^2 + 10289^2 .

It is a cyclic number.

It is not a de Polignac number, because 231751921 - 2⁵ = 231751889 is a prime.

It is not a weakly prime, because it can be changed into another prime (231751901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115875960 + 115875961.

It is an arithmetic number, because the mean of its divisors is an integer number (115875961).

Almost surely, 2^231751921 is an apocalyptic number.

It is an amenable number.

231751921 is a deficient number, since it is larger than the sum of its proper divisors (1).

231751921 is an equidigital number, since it uses as much as digits as its factorization.

231751921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3780, while the sum is 31.

The square root of 231751921 is about 15223.4004414257. The cubic root of 231751921 is about 614.2442705641.

The spelling of 231751921 in words is "two hundred thirty-one million, seven hundred fifty-one thousand, nine hundred twenty-one".