31159561 has 2 divisors, whose sum is σ = 31159562. Its totient is φ = 31159560.

The previous prime is 31159553. The next prime is 31159571. The reversal of 31159561 is 16595113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23425600 + 7733961 = 4840^2 + 2781^2 .

It is a cyclic number.

It is not a de Polignac number, because 31159561 - 2³ = 31159553 is a prime.

It is not a weakly prime, because it can be changed into another prime (31159501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15579780 + 15579781.

It is an arithmetic number, because the mean of its divisors is an integer number (15579781).

Almost surely, 2^31159561 is an apocalyptic number.

It is an amenable number.

31159561 is a deficient number, since it is larger than the sum of its proper divisors (1).

31159561 is an equidigital number, since it uses as much as digits as its factorization.

31159561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4050, while the sum is 31.

The square root of 31159561 is about 5582.0749726244. The cubic root of 31159561 is about 314.6761128774.

The spelling of 31159561 in words is "thirty-one million, one hundred fifty-nine thousand, five hundred sixty-one".