18219793 has 2 divisors, whose sum is σ = 18219794. Its totient is φ = 18219792.

The previous prime is 18219791. The next prime is 18219797. The reversal of 18219793 is 39791281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18215824 + 3969 = 4268^2 + 63^2 .

It is a cyclic number.

It is not a de Polignac number, because 18219793 - 2¹ = 18219791 is a prime.

Together with 18219791, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18219791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9109896 + 9109897.

It is an arithmetic number, because the mean of its divisors is an integer number (9109897).

Almost surely, 2^18219793 is an apocalyptic number.

It is an amenable number.

18219793 is a deficient number, since it is larger than the sum of its proper divisors (1).

18219793 is an equidigital number, since it uses as much as digits as its factorization.

18219793 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 40.

The square root of 18219793 is about 4268.4649465587. The cubic root of 18219793 is about 263.1365317304.

The spelling of 18219793 in words is "eighteen million, two hundred nineteen thousand, seven hundred ninety-three".