21286631 has 4 divisors (see below), whose sum is σ = 22407000. Its totient is φ = 20166264.

The previous prime is 21286627. The next prime is 21286633. The reversal of 21286631 is 13668212.

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 21286631 - 2² = 21286627 is a prime.

It is a super-2 number, since 2×21286631² = 906241318660322, 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 = 21286594 and 21286603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21286633) 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, 560156 + ... + 560193.

It is an arithmetic number, because the mean of its divisors is an integer number (5601750).

Almost surely, 2^21286631 is an apocalyptic number.

21286631 is a deficient number, since it is larger than the sum of its proper divisors (1120369).

21286631 is a wasteful number, since it uses less digits than its factorization.

21286631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1120368.

The product of its digits is 3456, while the sum is 29.

The square root of 21286631 is about 4613.7437076630. The cubic root of 21286631 is about 277.1419769418.

The spelling of 21286631 in words is "twenty-one million, two hundred eighty-six thousand, six hundred thirty-one".