231087721 has 2 divisors, whose sum is σ = 231087722. Its totient is φ = 231087720.

The previous prime is 231087713. The next prime is 231087751. The reversal of 231087721 is 127780132.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 208658025 + 22429696 = 14445^2 + 4736^2 .

It is a cyclic number.

It is not a de Polignac number, because 231087721 - 2³ = 231087713 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (231087751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115543860 + 115543861.

It is an arithmetic number, because the mean of its divisors is an integer number (115543861).

Almost surely, 2^231087721 is an apocalyptic number.

It is an amenable number.

231087721 is a deficient number, since it is larger than the sum of its proper divisors (1).

231087721 is an equidigital number, since it uses as much as digits as its factorization.

231087721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4704, while the sum is 31.

The square root of 231087721 is about 15201.5696886868. The cubic root of 231087721 is about 613.6569019362.

The spelling of 231087721 in words is "two hundred thirty-one million, eighty-seven thousand, seven hundred twenty-one".