21593431 has 4 divisors (see below), whose sum is σ = 21614112. Its totient is φ = 21572752.

The previous prime is 21593413. The next prime is 21593441. The reversal of 21593431 is 13439512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21593431 - 2⁷ = 21593303 is a prime.

It is a super-2 number, since 2×21593431² = 932552524703522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21593431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21593401) 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, 8686 + ... + 10891.

It is an arithmetic number, because the mean of its divisors is an integer number (5403528).

Almost surely, 2^21593431 is an apocalyptic number.

21593431 is a deficient number, since it is larger than the sum of its proper divisors (20681).

21593431 is a wasteful number, since it uses less digits than its factorization.

21593431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20680.

The product of its digits is 3240, while the sum is 28.

The square root of 21593431 is about 4646.8732498315. The cubic root of 21593431 is about 278.4670951200.

The spelling of 21593431 in words is "twenty-one million, five hundred ninety-three thousand, four hundred thirty-one".