1981977920 has 168 divisors, whose sum is σ = 5196315744. Its totient is φ = 719566848.

The previous prime is 1981977917. The next prime is 1981977923. The reversal of 1981977920 is 297791891.

It is an interprime number because it is at equal distance from previous prime (1981977917) and next prime (1981977923).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981977923) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3623087 + ... + 3623633.

Almost surely, 2^1981977920 is an apocalyptic number.

1981977920 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 1981977920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2598157872).

1981977920 is an abundant number, since it is smaller than the sum of its proper divisors (3214337824).

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

1981977920 is a wasteful number, since it uses less digits than its factorization.

1981977920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 657 (or 634 counting only the distinct ones).

The product of its (nonzero) digits is 571536, while the sum is 53.

The square root of 1981977920 is about 44519.4105980751. The cubic root of 1981977920 is about 1256.1252258607.

The spelling of 1981977920 in words is "one billion, nine hundred eighty-one million, nine hundred seventy-seven thousand, nine hundred twenty".