18646640 has 20 divisors (see below), whose sum is σ = 43353624. Its totient is φ = 7458624.

The previous prime is 18646633. The next prime is 18646651. The reversal of 18646640 is 4664681.

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 18646640.

It is a congruent number.

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, 116462 + ... + 116621.

Almost surely, 2^18646640 is an apocalyptic number.

18646640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18646640 is an abundant number, since it is smaller than the sum of its proper divisors (24706984).

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

18646640 is a wasteful number, since it uses less digits than its factorization.

18646640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 233096 (or 233090 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 35.

The square root of 18646640 is about 4318.1755406653. The cubic root of 18646640 is about 265.1755808038.

The spelling of 18646640 in words is "eighteen million, six hundred forty-six thousand, six hundred forty".