251281139 has 2 divisors, whose sum is σ = 251281140. Its totient is φ = 251281138.

The previous prime is 251281117. The next prime is 251281157. The reversal of 251281139 is 931182152.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251281139 is a prime.

It is not a weakly prime, because it can be changed into another prime (251281039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125640569 + 125640570.

It is an arithmetic number, because the mean of its divisors is an integer number (125640570).

Almost surely, 2^251281139 is an apocalyptic number.

251281139 is a deficient number, since it is larger than the sum of its proper divisors (1).

251281139 is an equidigital number, since it uses as much as digits as its factorization.

251281139 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 32.

The square root of 251281139 is about 15851.8497027949. The cubic root of 251281139 is about 631.0347813321.

The spelling of 251281139 in words is "two hundred fifty-one million, two hundred eighty-one thousand, one hundred thirty-nine".