21103631 has 2 divisors, whose sum is σ = 21103632. Its totient is φ = 21103630.

The previous prime is 21103603. The next prime is 21103633. The reversal of 21103631 is 13630112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21103631 - 2¹⁰ = 21102607 is a prime.

It is a super-2 number, since 2×21103631² = 890726482768322, which contains 22 as substring.

Together with 21103633, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21103633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551815 + 10551816.

It is an arithmetic number, because the mean of its divisors is an integer number (10551816).

Almost surely, 2^21103631 is an apocalyptic number.

21103631 is a deficient number, since it is larger than the sum of its proper divisors (1).

21103631 is an equidigital number, since it uses as much as digits as its factorization.

21103631 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 21103631 is about 4593.8688488027. The cubic root of 21103631 is about 276.3454986739.

Adding to 21103631 its reverse (13630112), we get a palindrome (34733743).

The spelling of 21103631 in words is "twenty-one million, one hundred three thousand, six hundred thirty-one".