18339791257 has 4 divisors (see below), whose sum is σ = 18359533620. Its totient is φ = 18320048896.

The previous prime is 18339791251. The next prime is 18339791269. The reversal of 18339791257 is 75219793381.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75219793381 = 1777 ⋅42329653.

It can be written as a sum of positive squares in 2 ways, for example, as 1518738841 + 16821052416 = 38971^2 + 129696^2 .

It is a cyclic number.

It is not a de Polignac number, because 18339791257 - 2¹⁹ = 18339266969 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18339791198 and 18339791207.

It is not an unprimeable number, because it can be changed into a prime (18339791251) 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, 9869788 + ... + 9871645.

It is an arithmetic number, because the mean of its divisors is an integer number (4589883405).

Almost surely, 2^18339791257 is an apocalyptic number.

It is an amenable number.

18339791257 is a deficient number, since it is larger than the sum of its proper divisors (19742363).

18339791257 is an equidigital number, since it uses as much as digits as its factorization.

18339791257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19742362.

The product of its digits is 2857680, while the sum is 55.

The spelling of 18339791257 in words is "eighteen billion, three hundred thirty-nine million, seven hundred ninety-one thousand, two hundred fifty-seven".