18309150721 has 4 divisors (see below), whose sum is σ = 18312298672. Its totient is φ = 18306002772.

The previous prime is 18309150703. The next prime is 18309150733. The reversal of 18309150721 is 12705190381.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18309150721 - 2³¹ = 16161667073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18309150701) 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, 1565235 + ... + 1576888.

It is an arithmetic number, because the mean of its divisors is an integer number (4578074668).

Almost surely, 2^18309150721 is an apocalyptic number.

It is an amenable number.

18309150721 is a deficient number, since it is larger than the sum of its proper divisors (3147951).

18309150721 is an equidigital number, since it uses as much as digits as its factorization.

18309150721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3147950.

The product of its (nonzero) digits is 15120, while the sum is 37.

The spelling of 18309150721 in words is "eighteen billion, three hundred nine million, one hundred fifty thousand, seven hundred twenty-one".