31137881 has 2 divisors, whose sum is σ = 31137882. Its totient is φ = 31137880.

The previous prime is 31137859. The next prime is 31137889. The reversal of 31137881 is 18873113.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25806400 + 5331481 = 5080^2 + 2309^2 .

It is a cyclic number.

It is not a de Polignac number, because 31137881 - 2¹⁸ = 30875737 is a prime.

It is a super-2 number, since 2×31137881² = 1939135266340322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (31137889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15568940 + 15568941.

It is an arithmetic number, because the mean of its divisors is an integer number (15568941).

Almost surely, 2^31137881 is an apocalyptic number.

It is an amenable number.

31137881 is a deficient number, since it is larger than the sum of its proper divisors (1).

31137881 is an equidigital number, since it uses as much as digits as its factorization.

31137881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 32.

The square root of 31137881 is about 5580.1327045152. The cubic root of 31137881 is about 314.6031148338.

The spelling of 31137881 in words is "thirty-one million, one hundred thirty-seven thousand, eight hundred eighty-one".