21369377 has 2 divisors, whose sum is σ = 21369378. Its totient is φ = 21369376.

The previous prime is 21369373. The next prime is 21369379. The reversal of 21369377 is 77396312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12103441 + 9265936 = 3479^2 + 3044^2 .

It is a cyclic number.

It is not a de Polignac number, because 21369377 - 2² = 21369373 is a prime.

Together with 21369379, it forms a pair of twin primes.

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 21369377.

It is not a weakly prime, because it can be changed into another prime (21369371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10684688 + 10684689.

It is an arithmetic number, because the mean of its divisors is an integer number (10684689).

Almost surely, 2^21369377 is an apocalyptic number.

It is an amenable number.

21369377 is a deficient number, since it is larger than the sum of its proper divisors (1).

21369377 is an equidigital number, since it uses as much as digits as its factorization.

21369377 is an evil number, because the sum of its binary digits is even.

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

The square root of 21369377 is about 4622.7023481942. The cubic root of 21369377 is about 277.5006173728.

The spelling of 21369377 in words is "twenty-one million, three hundred sixty-nine thousand, three hundred seventy-seven".