21056039 has 2 divisors, whose sum is σ = 21056040. Its totient is φ = 21056038.

The previous prime is 21056033. The next prime is 21056051. The reversal of 21056039 is 93065012.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21056039 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21055999 and 21056017.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21056033) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10528019 + 10528020.

It is an arithmetic number, because the mean of its divisors is an integer number (10528020).

Almost surely, 2^21056039 is an apocalyptic number.

21056039 is a deficient number, since it is larger than the sum of its proper divisors (1).

21056039 is an equidigital number, since it uses as much as digits as its factorization.

21056039 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1620, while the sum is 26.

The square root of 21056039 is about 4588.6859774885. The cubic root of 21056039 is about 276.1376081635.

The spelling of 21056039 in words is "twenty-one million, fifty-six thousand, thirty-nine".