18910640 has 40 divisors (see below), whose sum is σ = 50249760. Its totient is φ = 6483456.

The previous prime is 18910609. The next prime is 18910649. The reversal of 18910640 is 4601981.

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×18910640² = 715224610419200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18910649) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16325 + ... + 17444.

It is an arithmetic number, because the mean of its divisors is an integer number (1256244).

Almost surely, 2^18910640 is an apocalyptic number.

18910640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18910640 is an abundant number, since it is smaller than the sum of its proper divisors (31339120).

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

18910640 is a wasteful number, since it uses less digits than its factorization.

18910640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33789 (or 33783 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 18910640 is about 4348.6365679371. The cubic root of 18910640 is about 266.4211768524.

The spelling of 18910640 in words is "eighteen million, nine hundred ten thousand, six hundred forty".