31721723872 has 36 divisors (see below), whose sum is σ = 62622659736. Its totient is φ = 15817673600.

The previous prime is 31721723867. The next prime is 31721723881. The reversal of 31721723872 is 27832712713.

It is a super-2 number, since 2×31721723872² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4838997 + ... + 4845547.

It is an arithmetic number, because the mean of its divisors is an integer number (1739518326).

Almost surely, 2^31721723872 is an apocalyptic number.

31721723872 is a gapful number since it is divisible by the number (32) formed by its first and last digit.

It is an amenable number.

31721723872 is a deficient number, since it is larger than the sum of its proper divisors (30900935864).

31721723872 is an frugal number, since it uses more digits than its factorization.

31721723872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7339 (or 6942 counting only the distinct ones).

The product of its digits is 197568, while the sum is 43.

The spelling of 31721723872 in words is "thirty-one billion, seven hundred twenty-one million, seven hundred twenty-three thousand, eight hundred seventy-two".