31156261 has 2 divisors, whose sum is σ = 31156262. Its totient is φ = 31156260.

The previous prime is 31156259. The next prime is 31156267. The reversal of 31156261 is 16265113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 26071236 + 5085025 = 5106^2 + 2255^2 .

It is an emirp because it is prime and its reverse (16265113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31156261 - 2¹ = 31156259 is a prime.

Together with 31156259, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31156267) 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, 15578130 + 15578131.

It is an arithmetic number, because the mean of its divisors is an integer number (15578131).

Almost surely, 2^31156261 is an apocalyptic number.

It is an amenable number.

31156261 is a deficient number, since it is larger than the sum of its proper divisors (1).

31156261 is an equidigital number, since it uses as much as digits as its factorization.

31156261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1080, while the sum is 25.

The square root of 31156261 is about 5581.7793757905. The cubic root of 31156261 is about 314.6650037367.

The spelling of 31156261 in words is "thirty-one million, one hundred fifty-six thousand, two hundred sixty-one".