31423631721 has 4 divisors (see below), whose sum is σ = 41898175632. Its totient is φ = 20949087812.

The previous prime is 31423631713. The next prime is 31423631749. The reversal of 31423631721 is 12713632413.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 31423631721 - 2³ = 31423631713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (31423631621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5237271951 + ... + 5237271956.

It is an arithmetic number, because the mean of its divisors is an integer number (10474543908).

Almost surely, 2^31423631721 is an apocalyptic number.

It is an amenable number.

31423631721 is a deficient number, since it is larger than the sum of its proper divisors (10474543911).

31423631721 is a wasteful number, since it uses less digits than its factorization.

31423631721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10474543910.

The product of its digits is 18144, while the sum is 33.

The spelling of 31423631721 in words is "thirty-one billion, four hundred twenty-three million, six hundred thirty-one thousand, seven hundred twenty-one".