251171491 has 2 divisors, whose sum is σ = 251171492. Its totient is φ = 251171490.

The previous prime is 251171467. The next prime is 251171513. The reversal of 251171491 is 194171152.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 251171491 - 2²¹ = 249074339 is a prime.

It is not a weakly prime, because it can be changed into another prime (251171441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125585745 + 125585746.

It is an arithmetic number, because the mean of its divisors is an integer number (125585746).

Almost surely, 2^251171491 is an apocalyptic number.

251171491 is a deficient number, since it is larger than the sum of its proper divisors (1).

251171491 is an equidigital number, since it uses as much as digits as its factorization.

251171491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2520, while the sum is 31.

The square root of 251171491 is about 15848.3908015924. The cubic root of 251171491 is about 630.9429827349.

The spelling of 251171491 in words is "two hundred fifty-one million, one hundred seventy-one thousand, four hundred ninety-one".