18401989731 has 8 divisors (see below), whose sum is σ = 24552901824. Its totient is φ = 12259535400.

The previous prime is 18401989717. The next prime is 18401989751. The reversal of 18401989731 is 13798910481.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18401989731 - 2⁵ = 18401989699 is a prime.

It is a super-2 number, since 2×18401989731² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18401989751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2109361 + ... + 2118066.

It is an arithmetic number, because the mean of its divisors is an integer number (3069112728).

Almost surely, 2^18401989731 is an apocalyptic number.

18401989731 is a deficient number, since it is larger than the sum of its proper divisors (6150912093).

18401989731 is a wasteful number, since it uses less digits than its factorization.

18401989731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4228881.

The product of its (nonzero) digits is 435456, while the sum is 51.

The spelling of 18401989731 in words is "eighteen billion, four hundred one million, nine hundred eighty-nine thousand, seven hundred thirty-one".