21257323 has 2 divisors, whose sum is σ = 21257324. Its totient is φ = 21257322.

The previous prime is 21257303. The next prime is 21257347. The reversal of 21257323 is 32375212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21257323 - 2²¹ = 19160171 is a prime.

It is a super-2 number, since 2×21257323² = 903747562252658, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21257303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10628661 + 10628662.

It is an arithmetic number, because the mean of its divisors is an integer number (10628662).

Almost surely, 2^21257323 is an apocalyptic number.

21257323 is a deficient number, since it is larger than the sum of its proper divisors (1).

21257323 is an equidigital number, since it uses as much as digits as its factorization.

21257323 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2520, while the sum is 25.

The square root of 21257323 is about 4610.5664510990. The cubic root of 21257323 is about 277.0147263737.

The spelling of 21257323 in words is "twenty-one million, two hundred fifty-seven thousand, three hundred twenty-three".