21680573 has 4 divisors (see below), whose sum is σ = 21891168. Its totient is φ = 21469980.

The previous prime is 21680497. The next prime is 21680587. The reversal of 21680573 is 37508612.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21680573 - 2²⁴ = 4903357 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 (21680173) 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, 105143 + ... + 105348.

It is an arithmetic number, because the mean of its divisors is an integer number (5472792).

Almost surely, 2^21680573 is an apocalyptic number.

It is an amenable number.

21680573 is a deficient number, since it is larger than the sum of its proper divisors (210595).

21680573 is a wasteful number, since it uses less digits than its factorization.

21680573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210594.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21680573 is about 4656.2402214662. The cubic root of 21680573 is about 278.8411843495.

The spelling of 21680573 in words is "twenty-one million, six hundred eighty thousand, five hundred seventy-three".