21366689 has 2 divisors, whose sum is σ = 21366690. Its totient is φ = 21366688.

The previous prime is 21366679. The next prime is 21366713. The reversal of 21366689 is 98666312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19140625 + 2226064 = 4375^2 + 1492^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21366689 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21366619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10683344 + 10683345.

It is an arithmetic number, because the mean of its divisors is an integer number (10683345).

Almost surely, 2^21366689 is an apocalyptic number.

It is an amenable number.

21366689 is a deficient number, since it is larger than the sum of its proper divisors (1).

21366689 is an equidigital number, since it uses as much as digits as its factorization.

21366689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 41.

The square root of 21366689 is about 4622.4116000201. The cubic root of 21366689 is about 277.4889815174.

The spelling of 21366689 in words is "twenty-one million, three hundred sixty-six thousand, six hundred eighty-nine".