21013031 has 16 divisors (see below), whose sum is σ = 23987040. Its totient is φ = 18247680.

The previous prime is 21013021. The next prime is 21013043. The reversal of 21013031 is 13031012.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21013031 is a prime.

It is a super-2 number, since 2×21013031² = 883094943613922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21013021) 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, 59351 + ... + 59703.

It is an arithmetic number, because the mean of its divisors is an integer number (1499190).

Almost surely, 2^21013031 is an apocalyptic number.

21013031 is a deficient number, since it is larger than the sum of its proper divisors (2974009).

21013031 is a wasteful number, since it uses less digits than its factorization.

21013031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 626.

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

The square root of 21013031 is about 4583.9972731231. The cubic root of 21013031 is about 275.9494717766.

Adding to 21013031 its reverse (13031012), we get a palindrome (34044043).

The spelling of 21013031 in words is "twenty-one million, thirteen thousand, thirty-one".