251105531 has 2 divisors, whose sum is σ = 251105532. Its totient is φ = 251105530.

The previous prime is 251105471. The next prime is 251105551. The reversal of 251105531 is 135501152.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 251105531 - 2¹⁰ = 251104507 is a prime.

It is a super-2 number, since 2×251105531² = 126107975397583922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 251105497 and 251105506.

It is not a weakly prime, because it can be changed into another prime (251105551) 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, 125552765 + 125552766.

It is an arithmetic number, because the mean of its divisors is an integer number (125552766).

Almost surely, 2^251105531 is an apocalyptic number.

251105531 is a deficient number, since it is larger than the sum of its proper divisors (1).

251105531 is an equidigital number, since it uses as much as digits as its factorization.

251105531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 750, while the sum is 23.

The square root of 251105531 is about 15846.3096965824. The cubic root of 251105531 is about 630.8877473755.

Adding to 251105531 its reverse (135501152), we get a palindrome (386606683).

It can be divided in two parts, 251 and 105531, that multiplied together give a triangular number (26488281 = T₇₂₇₈).

The spelling of 251105531 in words is "two hundred fifty-one million, one hundred five thousand, five hundred thirty-one".