20640593 has 4 divisors (see below), whose sum is σ = 21726960. Its totient is φ = 19554228.

The previous prime is 20640583. The next prime is 20640617. The reversal of 20640593 is 39504602.

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 20640593 - 2⁴ = 20640577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20640553) 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, 543155 + ... + 543192.

It is an arithmetic number, because the mean of its divisors is an integer number (5431740).

Almost surely, 2^20640593 is an apocalyptic number.

It is an amenable number.

20640593 is a deficient number, since it is larger than the sum of its proper divisors (1086367).

20640593 is a wasteful number, since it uses less digits than its factorization.

20640593 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1086366.

The product of its (nonzero) digits is 6480, while the sum is 29.

The square root of 20640593 is about 4543.1919395949. The cubic root of 20640593 is about 274.3094209911.

The spelling of 20640593 in words is "twenty million, six hundred forty thousand, five hundred ninety-three".