31423729 has 2 divisors, whose sum is σ = 31423730. Its totient is φ = 31423728.

The previous prime is 31423709. The next prime is 31423747. The reversal of 31423729 is 92732413.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 29866225 + 1557504 = 5465^2 + 1248^2 .

It is a cyclic number.

It is not a de Polignac number, because 31423729 - 2⁵ = 31423697 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31423729.

It is not a weakly prime, because it can be changed into another prime (31423709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15711864 + 15711865.

It is an arithmetic number, because the mean of its divisors is an integer number (15711865).

Almost surely, 2^31423729 is an apocalyptic number.

It is an amenable number.

31423729 is a deficient number, since it is larger than the sum of its proper divisors (1).

31423729 is an equidigital number, since it uses as much as digits as its factorization.

31423729 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9072, while the sum is 31.

The square root of 31423729 is about 5605.6872014054. The cubic root of 31423729 is about 315.5628770196.

The spelling of 31423729 in words is "thirty-one million, four hundred twenty-three thousand, seven hundred twenty-nine".