21073831 has 16 divisors (see below), whose sum is σ = 23541760. Its totient is φ = 18779040.

The previous prime is 21073799. The next prime is 21073837. The reversal of 21073831 is 13837012.

It is a cyclic number.

It is not a de Polignac number, because 21073831 - 2⁵ = 21073799 is a prime.

It is a super-2 number, since 2×21073831² = 888212706033122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21073796 and 21073805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21073837) 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, 21310 + ... + 22276.

It is an arithmetic number, because the mean of its divisors is an integer number (1471360).

Almost surely, 2^21073831 is an apocalyptic number.

21073831 is a deficient number, since it is larger than the sum of its proper divisors (2467929).

21073831 is a wasteful number, since it uses less digits than its factorization.

21073831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1054.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21073831 is about 4590.6242494894. The cubic root of 21073831 is about 276.2153634836.

It can be divided in two parts, 21073 and 831, that added together give a square (21904 = 148²).

The spelling of 21073831 in words is "twenty-one million, seventy-three thousand, eight hundred thirty-one".