251261 has 2 divisors, whose sum is σ = 251262. Its totient is φ = 251260.

The previous prime is 251257. The next prime is 251263. The reversal of 251261 is 162152.

251261 is nontrivially palindromic in base 6.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 244036 + 7225 = 494^2 + 85^2 .

It is a cyclic number.

It is not a de Polignac number, because 251261 - 2² = 251257 is a prime.

Together with 251263, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125630 + 125631.

It is an arithmetic number, because the mean of its divisors is an integer number (125631).

2²⁵¹²⁶¹ is an apocalyptic number.

It is an amenable number.

251261 is a deficient number, since it is larger than the sum of its proper divisors (1).

251261 is an equidigital number, since it uses as much as digits as its factorization.

251261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120, while the sum is 17.

The square root of 251261 is about 501.2594138767. The cubic root of 251261 is about 63.1017922726.

It can be divided in two parts, 251 and 261, that added together give a 9-th power (512 = 2⁹).

The spelling of 251261 in words is "two hundred fifty-one thousand, two hundred sixty-one".