21022739 has 2 divisors, whose sum is σ = 21022740. Its totient is φ = 21022738.

The previous prime is 21022733. The next prime is 21022741. The reversal of 21022739 is 93722012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21022739 - 2⁴ = 21022723 is a prime.

Together with 21022741, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21022733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10511369 + 10511370.

It is an arithmetic number, because the mean of its divisors is an integer number (10511370).

Almost surely, 2^21022739 is an apocalyptic number.

21022739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21022739 is an equidigital number, since it uses as much as digits as its factorization.

21022739 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 21022739 is about 4585.0560520020. The cubic root of 21022739 is about 275.9919613636.

The spelling of 21022739 in words is "twenty-one million, twenty-two thousand, seven hundred thirty-nine".