21265567 has 4 divisors (see below), whose sum is σ = 21342616. Its totient is φ = 21188520.

The previous prime is 21265553. The next prime is 21265577. The reversal of 21265567 is 76556212.

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

It is a cyclic number.

It is not a de Polignac number, because 21265567 - 2¹¹ = 21263519 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21265537) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38109 + ... + 38662.

It is an arithmetic number, because the mean of its divisors is an integer number (5335654).

Almost surely, 2^21265567 is an apocalyptic number.

21265567 is a deficient number, since it is larger than the sum of its proper divisors (77049).

21265567 is an equidigital number, since it uses as much as digits as its factorization.

21265567 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77048.

The product of its digits is 25200, while the sum is 34.

The square root of 21265567 is about 4611.4603977482. The cubic root of 21265567 is about 277.0505322972.

The spelling of 21265567 in words is "twenty-one million, two hundred sixty-five thousand, five hundred sixty-seven".