21130031 has 16 divisors (see below), whose sum is σ = 25147584. Its totient is φ = 17554944.

The previous prime is 21130027. The next prime is 21130037. The reversal of 21130031 is 13003112.

It is a cyclic number.

It is not a de Polignac number, because 21130031 - 2² = 21130027 is a prime.

It is a super-2 number, since 2×21130031² = 892956420121922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21129994 and 21130021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21130037) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3005 + ... + 7161.

It is an arithmetic number, because the mean of its divisors is an integer number (1571724).

Almost surely, 2^21130031 is an apocalyptic number.

21130031 is a deficient number, since it is larger than the sum of its proper divisors (4017553).

21130031 is a wasteful number, since it uses less digits than its factorization.

21130031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4210.

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

The square root of 21130031 is about 4596.7413457796. The cubic root of 21130031 is about 276.4606839252.

Adding to 21130031 its reverse (13003112), we get a palindrome (34133143).

The spelling of 21130031 in words is "twenty-one million, one hundred thirty thousand, thirty-one".