21631039 has 2 divisors, whose sum is σ = 21631040. Its totient is φ = 21631038.

The previous prime is 21631037. The next prime is 21631061. The reversal of 21631039 is 93013612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21631039 - 2¹ = 21631037 is a prime.

Together with 21631037, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21631033) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10815519 + 10815520.

It is an arithmetic number, because the mean of its divisors is an integer number (10815520).

Almost surely, 2^21631039 is an apocalyptic number.

21631039 is a deficient number, since it is larger than the sum of its proper divisors (1).

21631039 is an equidigital number, since it uses as much as digits as its factorization.

21631039 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972, while the sum is 25.

The square root of 21631039 is about 4650.9180814115. The cubic root of 21631039 is about 278.6286645738.

The spelling of 21631039 in words is "twenty-one million, six hundred thirty-one thousand, thirty-nine".