251459981 has 2 divisors, whose sum is σ = 251459982. Its totient is φ = 251459980.

The previous prime is 251459963. The next prime is 251459993. The reversal of 251459981 is 189954152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 212284900 + 39175081 = 14570^2 + 6259^2 .

It is a cyclic number.

It is not a de Polignac number, because 251459981 - 2¹⁰ = 251458957 is a prime.

It is a super-2 number, since 2×251459981² = 126464244089040722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251459381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125729990 + 125729991.

It is an arithmetic number, because the mean of its divisors is an integer number (125729991).

Almost surely, 2^251459981 is an apocalyptic number.

It is an amenable number.

251459981 is a deficient number, since it is larger than the sum of its proper divisors (1).

251459981 is an equidigital number, since it uses as much as digits as its factorization.

251459981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 129600, while the sum is 44.

The square root of 251459981 is about 15857.4897445970. The cubic root of 251459981 is about 631.1844526783.

The spelling of 251459981 in words is "two hundred fifty-one million, four hundred fifty-nine thousand, nine hundred eighty-one".