21890593 has 4 divisors (see below), whose sum is σ = 22261680. Its totient is φ = 21519508.

The previous prime is 21890573. The next prime is 21890599. The reversal of 21890593 is 39509812.

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 a de Polignac number, because none of the positive numbers 2^k-21890593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21890599) 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, 185455 + ... + 185572.

It is an arithmetic number, because the mean of its divisors is an integer number (5565420).

Almost surely, 2^21890593 is an apocalyptic number.

It is an amenable number.

21890593 is a deficient number, since it is larger than the sum of its proper divisors (371087).

21890593 is an equidigital number, since it uses as much as digits as its factorization.

21890593 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 371086.

The product of its (nonzero) digits is 19440, while the sum is 37.

The square root of 21890593 is about 4678.7383983292. The cubic root of 21890593 is about 279.7386719910.

The spelling of 21890593 in words is "twenty-one million, eight hundred ninety thousand, five hundred ninety-three".