19904840 has 32 divisors (see below), whose sum is σ = 45360000. Its totient is φ = 7859904.

The previous prime is 19904831. The next prime is 19904851. The reversal of 19904840 is 4840991.

It is a self number, because there is not a number n which added to its sum of digits gives 19904840.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11 + ... + 6309.

It is an arithmetic number, because the mean of its divisors is an integer number (1417500).

Almost surely, 2^19904840 is an apocalyptic number.

19904840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19904840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22680000).

19904840 is an abundant number, since it is smaller than the sum of its proper divisors (25455160).

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

19904840 is a wasteful number, since it uses less digits than its factorization.

19904840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6389 (or 6385 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 19904840 is about 4461.4840580237. The cubic root of 19904840 is about 271.0105704314.

The spelling of 19904840 in words is "nineteen million, nine hundred four thousand, eight hundred forty".