21264689 has 2 divisors, whose sum is σ = 21264690. Its totient is φ = 21264688.

The previous prime is 21264613. The next prime is 21264703. The reversal of 21264689 is 98646212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16875664 + 4389025 = 4108^2 + 2095^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21264689 is a prime.

It is not a weakly prime, because it can be changed into another prime (21264889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10632344 + 10632345.

It is an arithmetic number, because the mean of its divisors is an integer number (10632345).

Almost surely, 2^21264689 is an apocalyptic number.

It is an amenable number.

21264689 is a deficient number, since it is larger than the sum of its proper divisors (1).

21264689 is an equidigital number, since it uses as much as digits as its factorization.

21264689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 41472, while the sum is 38.

The square root of 21264689 is about 4611.3651991574. The cubic root of 21264689 is about 277.0467193459.

The spelling of 21264689 in words is "twenty-one million, two hundred sixty-four thousand, six hundred eighty-nine".