1981880 has 16 divisors (see below), whose sum is σ = 4459320. Its totient is φ = 792736.

The previous prime is 1981879. The next prime is 1981883. The reversal of 1981880 is 881891.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 1981880.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981883) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 24734 + ... + 24813.

2^1981880 is an apocalyptic number.

1981880 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1981880 is an abundant number, since it is smaller than the sum of its proper divisors (2477440).

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

1981880 is a wasteful number, since it uses less digits than its factorization.

1981880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49558 (or 49554 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 35.

The square root of 1981880 is about 1407.7925983610. The cubic root of 1981880 is about 125.6104539151.

The spelling of 1981880 in words is "one million, nine hundred eighty-one thousand, eight hundred eighty".