18644431 has 4 divisors (see below), whose sum is σ = 20078632. Its totient is φ = 17210232.

The previous prime is 18644363. The next prime is 18644441. The reversal of 18644431 is 13444681.

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

It is not a de Polignac number, because 18644431 - 2¹⁹ = 18120143 is a prime.

It is a super-2 number, since 2×18644431² = 695229614627522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18644393 and 18644402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18644441) 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, 717081 + ... + 717106.

It is an arithmetic number, because the mean of its divisors is an integer number (5019658).

Almost surely, 2^18644431 is an apocalyptic number.

18644431 is a deficient number, since it is larger than the sum of its proper divisors (1434201).

18644431 is a wasteful number, since it uses less digits than its factorization.

18644431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1434200.

The product of its digits is 9216, while the sum is 31.

The square root of 18644431 is about 4317.9197537703. The cubic root of 18644431 is about 265.1651089263.

The spelling of 18644431 in words is "eighteen million, six hundred forty-four thousand, four hundred thirty-one".