18398440 has 16 divisors (see below), whose sum is σ = 41396580. Its totient is φ = 7359360.

The previous prime is 18398423. The next prime is 18398447. The reversal of 18398440 is 4489381.

It can be written as a sum of positive squares in 2 ways, for example, as 16597476 + 1800964 = 4074^2 + 1342^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 18398440.

It is not an unprimeable number, because it can be changed into a prime (18398447) 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, 229941 + ... + 230020.

Almost surely, 2^18398440 is an apocalyptic number.

18398440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18398440 is an abundant number, since it is smaller than the sum of its proper divisors (22998140).

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

18398440 is a wasteful number, since it uses less digits than its factorization.

18398440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 459972 (or 459968 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 37.

The square root of 18398440 is about 4289.3402756135. The cubic root of 18398440 is about 263.9937632442.

The spelling of 18398440 in words is "eighteen million, three hundred ninety-eight thousand, four hundred forty".