21673265 has 4 divisors (see below), whose sum is σ = 26007924. Its totient is φ = 17338608.

The previous prime is 21673261. The next prime is 21673271. The reversal of 21673265 is 56237612.

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 4566769 + 17106496 = 2137^2 + 4136^2 .

It is a cyclic number.

It is not a de Polignac number, because 21673265 - 2² = 21673261 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21673261) 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, 2167322 + ... + 2167331.

It is an arithmetic number, because the mean of its divisors is an integer number (6501981).

Almost surely, 2^21673265 is an apocalyptic number.

It is an amenable number.

21673265 is a deficient number, since it is larger than the sum of its proper divisors (4334659).

21673265 is an equidigital number, since it uses as much as digits as its factorization.

21673265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4334658.

The product of its digits is 15120, while the sum is 32.

The square root of 21673265 is about 4655.4554019988. The cubic root of 21673265 is about 278.8098506085.

The spelling of 21673265 in words is "twenty-one million, six hundred seventy-three thousand, two hundred sixty-five".