251278081 has 2 divisors, whose sum is σ = 251278082. Its totient is φ = 251278080.

The previous prime is 251278039. The next prime is 251278091. The reversal of 251278081 is 180872152.

251278081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 154157056 + 97121025 = 12416^2 + 9855^2 .

It is a cyclic number.

It is not a de Polignac number, because 251278081 - 2¹⁹ = 250753793 is a prime.

It is a super-2 number, since 2×251278081² = 126281347982085122, which contains 22 as substring.

It is equal to p_13745419 and since 251278081 and 13745419 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (251278091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125639040 + 125639041.

It is an arithmetic number, because the mean of its divisors is an integer number (125639041).

Almost surely, 2^251278081 is an apocalyptic number.

It is an amenable number.

251278081 is a deficient number, since it is larger than the sum of its proper divisors (1).

251278081 is an equidigital number, since it uses as much as digits as its factorization.

251278081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8960, while the sum is 34.

The square root of 251278081 is about 15851.7532468809. The cubic root of 251278081 is about 631.0322215005.

The spelling of 251278081 in words is "two hundred fifty-one million, two hundred seventy-eight thousand, eighty-one".