18351444640 has 24 divisors (see below), whose sum is σ = 43355288340. Its totient is φ = 7340577792.

The previous prime is 18351444611. The next prime is 18351444689. The reversal of 18351444640 is 4644415381.

It can be written as a sum of positive squares in 2 ways, for example, as 18161335696 + 190108944 = 134764^2 + 13788^2 .

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 18351444593 and 18351444602.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 57348105 + ... + 57348424.

Almost surely, 2^18351444640 is an apocalyptic number.

18351444640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18351444640 is an abundant number, since it is smaller than the sum of its proper divisors (25003843700).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18351444640 is a wasteful number, since it uses less digits than its factorization.

18351444640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114696544 (or 114696536 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 40.

The spelling of 18351444640 in words is "eighteen billion, three hundred fifty-one million, four hundred forty-four thousand, six hundred forty".