21253697 has 2 divisors, whose sum is σ = 21253698. Its totient is φ = 21253696.

The previous prime is 21253667. The next prime is 21253711. The reversal of 21253697 is 79635212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21242881 + 10816 = 4609^2 + 104^2 .

It is a cyclic number.

It is not a de Polignac number, because 21253697 - 2²⁰ = 20205121 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21253627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10626848 + 10626849.

It is an arithmetic number, because the mean of its divisors is an integer number (10626849).

Almost surely, 2^21253697 is an apocalyptic number.

It is an amenable number.

21253697 is a deficient number, since it is larger than the sum of its proper divisors (1).

21253697 is an equidigital number, since it uses as much as digits as its factorization.

21253697 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22680, while the sum is 35.

The square root of 21253697 is about 4610.1732071583. The cubic root of 21253697 is about 276.9989747428.

The spelling of 21253697 in words is "twenty-one million, two hundred fifty-three thousand, six hundred ninety-seven".