19988820 has 36 divisors (see below), whose sum is σ = 60633300. Its totient is φ = 5330304.

The previous prime is 19988819. The next prime is 19988827. The reversal of 19988820 is 2888991.

It can be written as a sum of positive squares in 2 ways, for example, as 10771524 + 9217296 = 3282^2 + 3036^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19988827) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 55345 + ... + 55704.

Almost surely, 2^19988820 is an apocalyptic number.

19988820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19988820 is an abundant number, since it is smaller than the sum of its proper divisors (40644480).

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

19988820 is a wasteful number, since it uses less digits than its factorization.

19988820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111064 (or 111059 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 45.

The square root of 19988820 is about 4470.8858182691. The cubic root of 19988820 is about 271.3911735838.

The spelling of 19988820 in words is "nineteen million, nine hundred eighty-eight thousand, eight hundred twenty".