31639939 has 2 divisors, whose sum is σ = 31639940. Its totient is φ = 31639938.

The previous prime is 31639913. The next prime is 31639961. The reversal of 31639939 is 93993613.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31639939 - 2²³ = 23251331 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31639895 and 31639904.

It is not a weakly prime, because it can be changed into another prime (31639969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15819969 + 15819970.

It is an arithmetic number, because the mean of its divisors is an integer number (15819970).

Almost surely, 2^31639939 is an apocalyptic number.

31639939 is a deficient number, since it is larger than the sum of its proper divisors (1).

31639939 is an equidigital number, since it uses as much as digits as its factorization.

31639939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 118098, while the sum is 43.

The square root of 31639939 is about 5624.9390218917. The cubic root of 31639939 is about 316.2849636650.

The spelling of 31639939 in words is "thirty-one million, six hundred thirty-nine thousand, nine hundred thirty-nine".