19918540 has 12 divisors (see below), whose sum is σ = 41828976. Its totient is φ = 7967408.

The previous prime is 19918537. The next prime is 19918541. The reversal of 19918540 is 4581991.

It is a self number, because there is not a number n which added to its sum of digits gives 19918540.

It is not an unprimeable number, because it can be changed into a prime (19918541) 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, 497944 + ... + 497983.

It is an arithmetic number, because the mean of its divisors is an integer number (3485748).

Almost surely, 2^19918540 is an apocalyptic number.

19918540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19918540 is an abundant number, since it is smaller than the sum of its proper divisors (21910436).

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

19918540 is a wasteful number, since it uses less digits than its factorization.

19918540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 995936 (or 995934 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 37.

The square root of 19918540 is about 4463.0191574762. The cubic root of 19918540 is about 271.0727327551.

The spelling of 19918540 in words is "nineteen million, nine hundred eighteen thousand, five hundred forty".