21252997 has 2 divisors, whose sum is σ = 21252998. Its totient is φ = 21252996.

The previous prime is 21252983. The next prime is 21253007. The reversal of 21252997 is 79925212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12047841 + 9205156 = 3471^2 + 3034^2 .

It is a cyclic number.

It is not a de Polignac number, because 21252997 - 2²³ = 12864389 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21256997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10626498 + 10626499.

It is an arithmetic number, because the mean of its divisors is an integer number (10626499).

Almost surely, 2^21252997 is an apocalyptic number.

It is an amenable number.

21252997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21252997 is an equidigital number, since it uses as much as digits as its factorization.

21252997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22680, while the sum is 37.

The square root of 21252997 is about 4610.0972874767. The cubic root of 21252997 is about 276.9959336811.

The spelling of 21252997 in words is "twenty-one million, two hundred fifty-two thousand, nine hundred ninety-seven".