21033631 has 2 divisors, whose sum is σ = 21033632. Its totient is φ = 21033630.

The previous prime is 21033601. The next prime is 21033647. The reversal of 21033631 is 13633012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21033631 - 2⁵ = 21033599 is a prime.

It is a super-2 number, since 2×21033631² = 884827266088322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21033599 and 21033608.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21033601) 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, 10516815 + 10516816.

It is an arithmetic number, because the mean of its divisors is an integer number (10516816).

Almost surely, 2^21033631 is an apocalyptic number.

21033631 is a deficient number, since it is larger than the sum of its proper divisors (1).

21033631 is an equidigital number, since it uses as much as digits as its factorization.

21033631 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 19.

The square root of 21033631 is about 4586.2436699329. The cubic root of 21033631 is about 276.0396174664.

Adding to 21033631 its reverse (13633012), we get a palindrome (34666643).

The spelling of 21033631 in words is "twenty-one million, thirty-three thousand, six hundred thirty-one".