1981808640 has 352 divisors, whose sum is σ = 8053061760. Its totient is φ = 452984832.

The previous prime is 1981808603. The next prime is 1981808659. The reversal of 1981808640 is 468081891.

It is a Jordan-Polya number, since it can be written as 8! ⋅ 4! ⋅ (2!)¹¹.

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

It is a nialpdrome in base 16.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 283115517 + ... + 283115523.

Almost surely, 2^1981808640 is an apocalyptic number.

1981808640 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 1981808640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4026530880).

1981808640 is an abundant number, since it is smaller than the sum of its proper divisors (6071253120).

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

1981808640 is an frugal number, since it uses more digits than its factorization.

1981808640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63 (or 17 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 45.

The square root of 1981808640 is about 44517.5093642940. The cubic root of 1981808640 is about 1256.0894631124.

The spelling of 1981808640 in words is "one billion, nine hundred eighty-one million, eight hundred eight thousand, six hundred forty".