21336389 has 2 divisors, whose sum is σ = 21336390. Its totient is φ = 21336388.

The previous prime is 21336349. The next prime is 21336391. The reversal of 21336389 is 98363312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19492225 + 1844164 = 4415^2 + 1358^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21336389 is a prime.

It is a Sophie Germain prime.

Together with 21336391, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21336349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10668194 + 10668195.

It is an arithmetic number, because the mean of its divisors is an integer number (10668195).

Almost surely, 2^21336389 is an apocalyptic number.

It is an amenable number.

21336389 is a deficient number, since it is larger than the sum of its proper divisors (1).

21336389 is an equidigital number, since it uses as much as digits as its factorization.

21336389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23328, while the sum is 35.

The square root of 21336389 is about 4619.1329272927. The cubic root of 21336389 is about 277.3577508639.

The spelling of 21336389 in words is "twenty-one million, three hundred thirty-six thousand, three hundred eighty-nine".