251020921 has 2 divisors, whose sum is σ = 251020922. Its totient is φ = 251020920.

The previous prime is 251020909. The next prime is 251020933. The reversal of 251020921 is 129020152.

It is a balanced prime because it is at equal distance from previous prime (251020909) and next prime (251020933).

It can be written as a sum of positive squares in only one way, i.e., 157628025 + 93392896 = 12555^2 + 9664^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251020921 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 251020892 and 251020901.

It is not a weakly prime, because it can be changed into another prime (251027921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125510460 + 125510461.

It is an arithmetic number, because the mean of its divisors is an integer number (125510461).

Almost surely, 2^251020921 is an apocalyptic number.

It is an amenable number.

251020921 is a deficient number, since it is larger than the sum of its proper divisors (1).

251020921 is an equidigital number, since it uses as much as digits as its factorization.

251020921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 251020921 is about 15843.6397649025. The cubic root of 251020921 is about 630.8168802138.

The spelling of 251020921 in words is "two hundred fifty-one million, twenty thousand, nine hundred twenty-one".