21266365 has 4 divisors (see below), whose sum is σ = 25519644. Its totient is φ = 17013088.

The previous prime is 21266327. The next prime is 21266389. The reversal of 21266365 is 56366212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9308601 + 11957764 = 3051^2 + 3458^2 .

It is a cyclic number.

It is not a de Polignac number, because 21266365 - 2¹³ = 21258173 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2126632 + ... + 2126641.

It is an arithmetic number, because the mean of its divisors is an integer number (6379911).

Almost surely, 2^21266365 is an apocalyptic number.

It is an amenable number.

21266365 is a deficient number, since it is larger than the sum of its proper divisors (4253279).

21266365 is an equidigital number, since it uses as much as digits as its factorization.

21266365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4253278.

The product of its digits is 12960, while the sum is 31.

The square root of 21266365 is about 4611.5469205029. The cubic root of 21266365 is about 277.0539977360.

The spelling of 21266365 in words is "twenty-one million, two hundred sixty-six thousand, three hundred sixty-five".