31000000021 has 8 divisors (see below), whose sum is σ = 32881840704. Its totient is φ = 29124638400.

The previous prime is 30999999997. The next prime is 31000000027. The reversal of 31000000021 is 12000000013.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 31000000021 - 2²⁷ = 30865782293 is a prime.

It is a super-2 number, since 2×31000000021² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 30999999950 and 31000000013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31000000027) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1609905 + ... + 1629046.

It is an arithmetic number, because the mean of its divisors is an integer number (4110230088).

Almost surely, 2^31000000021 is an apocalyptic number.

It is an amenable number.

31000000021 is a deficient number, since it is larger than the sum of its proper divisors (1881840683).

31000000021 is a wasteful number, since it uses less digits than its factorization.

31000000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3239531.

The product of its (nonzero) digits is 6, while the sum is 7.

Adding to 31000000021 its reverse (12000000013), we get a palindrome (43000000034).

The spelling of 31000000021 in words is "thirty-one billion, twenty-one", and thus it is an aban number and an uban number.