1981642320 has 450 divisors, whose sum is σ = 8108844282. Its totient is φ = 447213312.

The previous prime is 1981642319. The next prime is 1981642331. The reversal of 1981642320 is 232461891.

1981642320 is a `hidden beast` number, since 1 + 9 + 8 + 1 + 642 + 3 + 2 + 0 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1585313856 + 396328464 = 39816^2 + 19908^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 89 ways as a sum of consecutive naturals, for example, 25084041 + ... + 25084119.

Almost surely, 2^1981642320 is an apocalyptic number.

1981642320 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 1981642320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4054422141).

1981642320 is an abundant number, since it is smaller than the sum of its proper divisors (6127201962).

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

1981642320 is an equidigital number, since it uses as much as digits as its factorization.

1981642320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197 (or 96 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 1981642320 is about 44515.6412960658. The cubic root of 1981642320 is about 1256.0543237218.

The spelling of 1981642320 in words is "one billion, nine hundred eighty-one million, six hundred forty-two thousand, three hundred twenty".