31961561 has 2 divisors, whose sum is σ = 31961562. Its totient is φ = 31961560.

The previous prime is 31961537. The next prime is 31961593. The reversal of 31961561 is 16516913.

It is a happy number.

It is an a-pointer prime, because the next prime (31961593) can be obtained adding 31961561 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23464336 + 8497225 = 4844^2 + 2915^2 .

It is a cyclic number.

It is not a de Polignac number, because 31961561 - 2⁶ = 31961497 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31961261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15980780 + 15980781.

It is an arithmetic number, because the mean of its divisors is an integer number (15980781).

Almost surely, 2^31961561 is an apocalyptic number.

It is an amenable number.

31961561 is a deficient number, since it is larger than the sum of its proper divisors (1).

31961561 is an equidigital number, since it uses as much as digits as its factorization.

31961561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4860, while the sum is 32.

The square root of 31961561 is about 5653.4556688808. The cubic root of 31961561 is about 317.3530383991.

The spelling of 31961561 in words is "thirty-one million, nine hundred sixty-one thousand, five hundred sixty-one".