18720255731 has 2 divisors, whose sum is σ = 18720255732. Its totient is φ = 18720255730.

The previous prime is 18720255713. The next prime is 18720255773. The reversal of 18720255731 is 13755202781.

Together with previous prime (18720255713) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18720255731 - 2²⁶ = 18653146867 is a prime.

It is a super-2 number, since 2×18720255731² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (18720255781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9360127865 + 9360127866.

It is an arithmetic number, because the mean of its divisors is an integer number (9360127866).

Almost surely, 2^18720255731 is an apocalyptic number.

18720255731 is a deficient number, since it is larger than the sum of its proper divisors (1).

18720255731 is an equidigital number, since it uses as much as digits as its factorization.

18720255731 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 117600, while the sum is 41.

The spelling of 18720255731 in words is "eighteen billion, seven hundred twenty million, two hundred fifty-five thousand, seven hundred thirty-one".