21112639 has 2 divisors, whose sum is σ = 21112640. Its totient is φ = 21112638.

The previous prime is 21112633. The next prime is 21112673. The reversal of 21112639 is 93621112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21112639 - 2⁹ = 21112127 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21112633) 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, 10556319 + 10556320.

It is an arithmetic number, because the mean of its divisors is an integer number (10556320).

Almost surely, 2^21112639 is an apocalyptic number.

21112639 is a deficient number, since it is larger than the sum of its proper divisors (1).

21112639 is an equidigital number, since it uses as much as digits as its factorization.

21112639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 648, while the sum is 25.

The square root of 21112639 is about 4594.8491814204. The cubic root of 21112639 is about 276.3848120690.

The spelling of 21112639 in words is "twenty-one million, one hundred twelve thousand, six hundred thirty-nine".