21002039 has 2 divisors, whose sum is σ = 21002040. Its totient is φ = 21002038.

The previous prime is 21001991. The next prime is 21002077. The reversal of 21002039 is 93020012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002039 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002099) 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, 10501019 + 10501020.

It is an arithmetic number, because the mean of its divisors is an integer number (10501020).

Almost surely, 2^21002039 is an apocalyptic number.

21002039 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002039 is an equidigital number, since it uses as much as digits as its factorization.

21002039 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 21002039 is about 4582.7981626949. The cubic root of 21002039 is about 275.9013466291.

The spelling of 21002039 in words is "twenty-one million, two thousand, thirty-nine".