31257661 has 2 divisors, whose sum is σ = 31257662. Its totient is φ = 31257660.

The previous prime is 31257659. The next prime is 31257691. The reversal of 31257661 is 16675213.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21335161 + 9922500 = 4619^2 + 3150^2 .

It is an emirp because it is prime and its reverse (16675213) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31257661 - 2¹ = 31257659 is a prime.

Together with 31257659, 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 (31257631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15628830 + 15628831.

It is an arithmetic number, because the mean of its divisors is an integer number (15628831).

Almost surely, 2^31257661 is an apocalyptic number.

It is an amenable number.

31257661 is a deficient number, since it is larger than the sum of its proper divisors (1).

31257661 is an equidigital number, since it uses as much as digits as its factorization.

31257661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 31.

The square root of 31257661 is about 5590.8551224298. The cubic root of 31257661 is about 315.0059997178.

The spelling of 31257661 in words is "thirty-one million, two hundred fifty-seven thousand, six hundred sixty-one".