31091261 has 2 divisors, whose sum is σ = 31091262. Its totient is φ = 31091260.

The previous prime is 31091257. The next prime is 31091267. The reversal of 31091261 is 16219013.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16605625 + 14485636 = 4075^2 + 3806^2 .

It is a cyclic number.

It is not a de Polignac number, because 31091261 - 2² = 31091257 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31091267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15545630 + 15545631.

It is an arithmetic number, because the mean of its divisors is an integer number (15545631).

Almost surely, 2^31091261 is an apocalyptic number.

It is an amenable number.

31091261 is a deficient number, since it is larger than the sum of its proper divisors (1).

31091261 is an equidigital number, since it uses as much as digits as its factorization.

31091261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 31091261 is about 5575.9538197514. The cubic root of 31091261 is about 314.4460272543.

The spelling of 31091261 in words is "thirty-one million, ninety-one thousand, two hundred sixty-one".