18720431 has 2 divisors, whose sum is σ = 18720432. Its totient is φ = 18720430.

The previous prime is 18720419. The next prime is 18720433. The reversal of 18720431 is 13402781.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18720431 - 2¹⁴ = 18704047 is a prime.

It is a super-2 number, since 2×18720431² = 700909073651522, which contains 22 as substring.

Together with 18720433, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18720431.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18720433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9360215 + 9360216.

It is an arithmetic number, because the mean of its divisors is an integer number (9360216).

Almost surely, 2^18720431 is an apocalyptic number.

18720431 is a deficient number, since it is larger than the sum of its proper divisors (1).

18720431 is an equidigital number, since it uses as much as digits as its factorization.

18720431 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 18720431 is about 4326.7113377252. The cubic root of 18720431 is about 265.5249165924.

The spelling of 18720431 in words is "eighteen million, seven hundred twenty thousand, four hundred thirty-one".