21386797 has 2 divisors, whose sum is σ = 21386798. Its totient is φ = 21386796.

The previous prime is 21386791. The next prime is 21386819. The reversal of 21386797 is 79768312.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21104836 + 281961 = 4594^2 + 531^2 .

It is a cyclic number.

It is not a de Polignac number, because 21386797 - 2⁷ = 21386669 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21386791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10693398 + 10693399.

It is an arithmetic number, because the mean of its divisors is an integer number (10693399).

Almost surely, 2^21386797 is an apocalyptic number.

It is an amenable number.

21386797 is a deficient number, since it is larger than the sum of its proper divisors (1).

21386797 is an equidigital number, since it uses as much as digits as its factorization.

21386797 is an evil number, because the sum of its binary digits is even.

The product of its digits is 127008, while the sum is 43.

The square root of 21386797 is about 4624.5861436457. The cubic root of 21386797 is about 277.5760016918.

The spelling of 21386797 in words is "twenty-one million, three hundred eighty-six thousand, seven hundred ninety-seven".