251145991 has 2 divisors, whose sum is σ = 251145992. Its totient is φ = 251145990.

The previous prime is 251145953. The next prime is 251146001. The reversal of 251145991 is 199541152.

251145991 = T₁₂₉₃₈ + T₁₂₉₃₉ + T₁₂₉₄₀.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 251145991 - 2²⁵ = 217591559 is a prime.

It is equal to p_13738618 and since 251145991 and 13738618 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 251145991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251145931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125572995 + 125572996.

It is an arithmetic number, because the mean of its divisors is an integer number (125572996).

Almost surely, 2^251145991 is an apocalyptic number.

251145991 is the 12940-th centered triangular number.

251145991 is a deficient number, since it is larger than the sum of its proper divisors (1).

251145991 is an equidigital number, since it uses as much as digits as its factorization.

251145991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16200, while the sum is 37.

The square root of 251145991 is about 15847.5862830906. The cubic root of 251145991 is about 630.9216300056.

The spelling of 251145991 in words is "two hundred fifty-one million, one hundred forty-five thousand, nine hundred ninety-one".