31130021 has 16 divisors (see below), whose sum is σ = 35199360. Its totient is φ = 27330240.

The previous prime is 31129991. The next prime is 31130039. The reversal of 31130021 is 12003113.

It is a cyclic number.

It is not a de Polignac number, because 31130021 - 2¹⁰ = 31128997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31129984 and 31130011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31130051) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26186 + ... + 27348.

It is an arithmetic number, because the mean of its divisors is an integer number (2199960).

Almost surely, 2^31130021 is an apocalyptic number.

It is an amenable number.

31130021 is a deficient number, since it is larger than the sum of its proper divisors (4069339).

31130021 is a wasteful number, since it uses less digits than its factorization.

31130021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1276.

The product of its (nonzero) digits is 18, while the sum is 11.

The square root of 31130021 is about 5579.4283757389. The cubic root of 31130021 is about 314.5766413071.

Adding to 31130021 its reverse (12003113), we get a palindrome (43133134).

The spelling of 31130021 in words is "thirty-one million, one hundred thirty thousand, twenty-one".