21367765 has 8 divisors (see below), whose sum is σ = 26266968. Its totient is φ = 16677120.

The previous prime is 21367763. The next prime is 21367771. The reversal of 21367765 is 56776312.

It can be written as a sum of positive squares in 4 ways, for example, as 628849 + 20738916 = 793^2 + 4554^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21367765 - 2¹ = 21367763 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 (21367763) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51912 + ... + 52321.

It is an arithmetic number, because the mean of its divisors is an integer number (3283371).

Almost surely, 2^21367765 is an apocalyptic number.

It is an amenable number.

21367765 is a deficient number, since it is larger than the sum of its proper divisors (4899203).

21367765 is a wasteful number, since it uses less digits than its factorization.

21367765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104279.

The product of its digits is 52920, while the sum is 37.

The square root of 21367765 is about 4622.5279880169. The cubic root of 21367765 is about 277.4936394397.

The spelling of 21367765 in words is "twenty-one million, three hundred sixty-seven thousand, seven hundred sixty-five".