21672765 has 40 divisors (see below), whose sum is σ = 39552480. Its totient is φ = 11350368.

The previous prime is 21672733. The next prime is 21672769. The reversal of 21672765 is 56727612.

It is not a de Polignac number, because 21672765 - 2⁵ = 21672733 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21672769) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 23442 + ... + 24348.

It is an arithmetic number, because the mean of its divisors is an integer number (988812).

Almost surely, 2^21672765 is an apocalyptic number.

It is an amenable number.

21672765 is a deficient number, since it is larger than the sum of its proper divisors (17879715).

21672765 is an equidigital number, since it uses as much as digits as its factorization.

21672765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 983 (or 974 counting only the distinct ones).

The product of its digits is 35280, while the sum is 36.

The square root of 21672765 is about 4655.4017012499. The cubic root of 21672765 is about 278.8077065538.

The spelling of 21672765 in words is "twenty-one million, six hundred seventy-two thousand, seven hundred sixty-five".