1981961800 has 288 divisors, whose sum is σ = 5913371520. Its totient is φ = 612057600.

The previous prime is 1981961791. The next prime is 1981961803. The reversal of 1981961800 is 81691891.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (1981961803) 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 71 ways as a sum of consecutive naturals, for example, 5987635 + ... + 5987965.

It is an arithmetic number, because the mean of its divisors is an integer number (20532540).

Almost surely, 2^1981961800 is an apocalyptic number.

1981961800 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 1981961800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2956685760).

1981961800 is an abundant number, since it is smaller than the sum of its proper divisors (3931409720).

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

1981961800 is a wasteful number, since it uses less digits than its factorization.

1981961800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 421 (or 405 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 43.

The square root of 1981961800 is about 44519.2295530819. The cubic root of 1981961800 is about 1256.1218203748.

The spelling of 1981961800 in words is "one billion, nine hundred eighty-one million, nine hundred sixty-one thousand, eight hundred".