21798631 has 2 divisors, whose sum is σ = 21798632. Its totient is φ = 21798630.

The previous prime is 21798619. The next prime is 21798653. The reversal of 21798631 is 13689712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21798631 - 2⁵ = 21798599 is a prime.

It is a super-2 number, since 2×21798631² = 950360626948322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21798331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10899315 + 10899316.

It is an arithmetic number, because the mean of its divisors is an integer number (10899316).

Almost surely, 2^21798631 is an apocalyptic number.

21798631 is a deficient number, since it is larger than the sum of its proper divisors (1).

21798631 is an equidigital number, since it uses as much as digits as its factorization.

21798631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 37.

The square root of 21798631 is about 4668.9004058772. The cubic root of 21798631 is about 279.3463963996.

The spelling of 21798631 in words is "twenty-one million, seven hundred ninety-eight thousand, six hundred thirty-one".