31991941 has 2 divisors, whose sum is σ = 31991942. Its totient is φ = 31991940.

The previous prime is 31991933. The next prime is 31991989. The reversal of 31991941 is 14919913.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31472100 + 519841 = 5610^2 + 721^2 .

It is an emirp because it is prime and its reverse (14919913) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31991941 - 2³ = 31991933 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31991941.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31991341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15995970 + 15995971.

It is an arithmetic number, because the mean of its divisors is an integer number (15995971).

Almost surely, 2^31991941 is an apocalyptic number.

It is an amenable number.

31991941 is a deficient number, since it is larger than the sum of its proper divisors (1).

31991941 is an equidigital number, since it uses as much as digits as its factorization.

31991941 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8748, while the sum is 37.

The square root of 31991941 is about 5656.1418829446. The cubic root of 31991941 is about 317.4535563537.

The spelling of 31991941 in words is "thirty-one million, nine hundred ninety-one thousand, nine hundred forty-one".