21423631 has 2 divisors, whose sum is σ = 21423632. Its totient is φ = 21423630.

The previous prime is 21423613. The next prime is 21423641. The reversal of 21423631 is 13632412.

Together with previous prime (21423613) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21423631 - 2⁹ = 21423119 is a prime.

It is a super-2 number, since 2×21423631² = 917943930448322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21423601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10711815 + 10711816.

It is an arithmetic number, because the mean of its divisors is an integer number (10711816).

Almost surely, 2^21423631 is an apocalyptic number.

21423631 is a deficient number, since it is larger than the sum of its proper divisors (1).

21423631 is an equidigital number, since it uses as much as digits as its factorization.

21423631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 22.

The square root of 21423631 is about 4628.5668408267. The cubic root of 21423631 is about 277.7352645990.

The spelling of 21423631 in words is "twenty-one million, four hundred twenty-three thousand, six hundred thirty-one".