21102239 has 2 divisors, whose sum is σ = 21102240. Its totient is φ = 21102238.

The previous prime is 21102209. The next prime is 21102251. The reversal of 21102239 is 93220112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21102239 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21102239.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21102209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551119 + 10551120.

It is an arithmetic number, because the mean of its divisors is an integer number (10551120).

Almost surely, 2^21102239 is an apocalyptic number.

21102239 is a deficient number, since it is larger than the sum of its proper divisors (1).

21102239 is an equidigital number, since it uses as much as digits as its factorization.

21102239 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 21102239 is about 4593.7173400200. The cubic root of 21102239 is about 276.3394226043.

The spelling of 21102239 in words is "twenty-one million, one hundred two thousand, two hundred thirty-nine".