31721129723 has 2 divisors, whose sum is σ = 31721129724. Its totient is φ = 31721129722.

The previous prime is 31721129707. The next prime is 31721129749. The reversal of 31721129723 is 32792112713.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31721129723 - 2⁴ = 31721129707 is a prime.

It is not a weakly prime, because it can be changed into another prime (31721129023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15860564861 + 15860564862.

It is an arithmetic number, because the mean of its divisors is an integer number (15860564862).

Almost surely, 2^31721129723 is an apocalyptic number.

31721129723 is a deficient number, since it is larger than the sum of its proper divisors (1).

31721129723 is an equidigital number, since it uses as much as digits as its factorization.

31721129723 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31752, while the sum is 38.

The spelling of 31721129723 in words is "thirty-one billion, seven hundred twenty-one million, one hundred twenty-nine thousand, seven hundred twenty-three".