21083731 has 4 divisors (see below), whose sum is σ = 21146632. Its totient is φ = 21020832.

The previous prime is 21083719. The next prime is 21083773. The reversal of 21083731 is 13738012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21083731 - 2¹⁵ = 21050963 is a prime.

It is a super-2 number, since 2×21083731² = 889047425760722, 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 = 21083696 and 21083705.

It is not an unprimeable number, because it can be changed into a prime (21083431) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30945 + ... + 31618.

It is an arithmetic number, because the mean of its divisors is an integer number (5286658).

Almost surely, 2^21083731 is an apocalyptic number.

21083731 is a deficient number, since it is larger than the sum of its proper divisors (62901).

21083731 is an equidigital number, since it uses as much as digits as its factorization.

21083731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62900.

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

The square root of 21083731 is about 4591.7024076044. The cubic root of 21083731 is about 276.2586099157.

The spelling of 21083731 in words is "twenty-one million, eighty-three thousand, seven hundred thirty-one".