19987920 has 240 divisors, whose sum is σ = 75209472. Its totient is φ = 4730880.

The previous prime is 19987907. The next prime is 19987949. The reversal of 19987920 is 2978991.

It is a tau number, because it is divible by the number of its divisors (240).

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

It is a congruent number.

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 47 ways as a sum of consecutive naturals, for example, 281485 + ... + 281555.

Almost surely, 2^19987920 is an apocalyptic number.

19987920 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 19987920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37604736).

19987920 is an abundant number, since it is smaller than the sum of its proper divisors (55221552).

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

19987920 is a wasteful number, since it uses less digits than its factorization.

19987920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130 (or 121 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 45.

The square root of 19987920 is about 4470.7851659412. The cubic root of 19987920 is about 271.3871003782.

The spelling of 19987920 in words is "nineteen million, nine hundred eighty-seven thousand, nine hundred twenty".