19985540 has 48 divisors (see below), whose sum is σ = 45505152. Its totient is φ = 7343616.

The previous prime is 19985533. The next prime is 19985543. The reversal of 19985540 is 4558991.

It is a happy number.

It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (19985543) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13937 + ... + 15303.

It is an arithmetic number, because the mean of its divisors is an integer number (948024).

Almost surely, 2^19985540 is an apocalyptic number.

19985540 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 19985540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22752576).

19985540 is an abundant number, since it is smaller than the sum of its proper divisors (25519612).

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

19985540 is a wasteful number, since it uses less digits than its factorization.

19985540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1436 (or 1434 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 41.

The square root of 19985540 is about 4470.5189855318. The cubic root of 19985540 is about 271.3763284230.

The spelling of 19985540 in words is "nineteen million, nine hundred eighty-five thousand, five hundred forty".