21395597 has 2 divisors, whose sum is σ = 21395598. Its totient is φ = 21395596.

The previous prime is 21395593. The next prime is 21395599. The reversal of 21395597 is 79559312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19616041 + 1779556 = 4429^2 + 1334^2 .

It is a cyclic number.

It is not a de Polignac number, because 21395597 - 2² = 21395593 is a prime.

Together with 21395599, it forms a pair of twin primes.

It is a Chen prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21395593) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10697798 + 10697799.

It is an arithmetic number, because the mean of its divisors is an integer number (10697799).

Almost surely, 2^21395597 is an apocalyptic number.

It is an amenable number.

21395597 is a deficient number, since it is larger than the sum of its proper divisors (1).

21395597 is an equidigital number, since it uses as much as digits as its factorization.

21395597 is an evil number, because the sum of its binary digits is even.

The product of its digits is 85050, while the sum is 41.

The square root of 21395597 is about 4625.5374822825. The cubic root of 21395597 is about 277.6140677606.

The spelling of 21395597 in words is "twenty-one million, three hundred ninety-five thousand, five hundred ninety-seven".