21367739 has 2 divisors, whose sum is σ = 21367740. Its totient is φ = 21367738.

The previous prime is 21367733. The next prime is 21367741. The reversal of 21367739 is 93776312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21367739 - 2²⁰ = 20319163 is a prime.

Together with 21367741, 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 (21367733) 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, 10683869 + 10683870.

It is an arithmetic number, because the mean of its divisors is an integer number (10683870).

Almost surely, 2^21367739 is an apocalyptic number.

21367739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21367739 is an equidigital number, since it uses as much as digits as its factorization.

21367739 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 47628, while the sum is 38.

The square root of 21367739 is about 4622.5251757021. The cubic root of 21367739 is about 277.4935268896.

It can be divided in two parts, 213677 and 39, that multiplied together give a triangular number (8333403 = T₄₀₈₂).

The spelling of 21367739 in words is "twenty-one million, three hundred sixty-seven thousand, seven hundred thirty-nine".