19881820 has 96 divisors (see below), whose sum is σ = 50803200. Its totient is φ = 6392064.

The previous prime is 19881817. The next prime is 19881833. The reversal of 19881820 is 2818891.

It is a self number, because there is not a number n which added to its sum of digits gives 19881820.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 239499 + ... + 239581.

It is an arithmetic number, because the mean of its divisors is an integer number (529200).

Almost surely, 2^19881820 is an apocalyptic number.

19881820 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 19881820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25401600).

19881820 is an abundant number, since it is smaller than the sum of its proper divisors (30921380).

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

19881820 is a wasteful number, since it uses less digits than its factorization.

19881820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 187 (or 185 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 19881820 is about 4458.9034526439. The cubic root of 19881820 is about 270.9060553170.

The spelling of 19881820 in words is "nineteen million, eight hundred eighty-one thousand, eight hundred twenty".