21576631 has 2 divisors, whose sum is σ = 21576632. Its totient is φ = 21576630.

The previous prime is 21576629. The next prime is 21576637. The reversal of 21576631 is 13667512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21576631 - 2¹ = 21576629 is a prime.

It is a super-2 number, since 2×21576631² = 931102010620322, which contains 22 as substring.

Together with 21576629, it forms a pair of twin primes.

It is a plaindrome in base 8.

It is a junction number, because it is equal to n+sod(n) for n = 21576593 and 21576602.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21576637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10788315 + 10788316.

It is an arithmetic number, because the mean of its divisors is an integer number (10788316).

Almost surely, 2^21576631 is an apocalyptic number.

21576631 is a deficient number, since it is larger than the sum of its proper divisors (1).

21576631 is an equidigital number, since it uses as much as digits as its factorization.

21576631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7560, while the sum is 31.

The square root of 21576631 is about 4645.0652309736. The cubic root of 21576631 is about 278.3948592477.

The spelling of 21576631 in words is "twenty-one million, five hundred seventy-six thousand, six hundred thirty-one".