31139789 has 2 divisors, whose sum is σ = 31139790. Its totient is φ = 31139788.

The previous prime is 31139761. The next prime is 31139807. The reversal of 31139789 is 98793113.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30360100 + 779689 = 5510^2 + 883^2 .

It is a cyclic number.

It is not a de Polignac number, because 31139789 - 2²⁴ = 14362573 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31139729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15569894 + 15569895.

It is an arithmetic number, because the mean of its divisors is an integer number (15569895).

Almost surely, 2^31139789 is an apocalyptic number.

It is an amenable number.

31139789 is a deficient number, since it is larger than the sum of its proper divisors (1).

31139789 is an equidigital number, since it uses as much as digits as its factorization.

31139789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40824, while the sum is 41.

The square root of 31139789 is about 5580.3036655723. The cubic root of 31139789 is about 314.6095405599.

The spelling of 31139789 in words is "thirty-one million, one hundred thirty-nine thousand, seven hundred eighty-nine".