21358573 has 4 divisors (see below), whose sum is σ = 21855328. Its totient is φ = 20861820.

The previous prime is 21358549. The next prime is 21358577. The reversal of 21358573 is 37585312.

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 21358573 - 2¹⁷ = 21227501 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 (21358577) 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, 248313 + ... + 248398.

It is an arithmetic number, because the mean of its divisors is an integer number (5463832).

Almost surely, 2^21358573 is an apocalyptic number.

It is an amenable number.

21358573 is a deficient number, since it is larger than the sum of its proper divisors (496755).

21358573 is an equidigital number, since it uses as much as digits as its factorization.

21358573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 496754.

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

The square root of 21358573 is about 4621.5336199145. The cubic root of 21358573 is about 277.4538429304.

The spelling of 21358573 in words is "twenty-one million, three hundred fifty-eight thousand, five hundred seventy-three".