1981961992 has 32 divisors (see below), whose sum is σ = 3751200000. Its totient is φ = 981687168.

The previous prime is 1981961987. The next prime is 1981961999. The reversal of 1981961992 is 2991691891.

It is a Smith number, since the sum of its digits (55) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (1981961999) 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 7 ways as a sum of consecutive naturals, for example, 377884 + ... + 383092.

It is an arithmetic number, because the mean of its divisors is an integer number (117225000).

Almost surely, 2^1981961992 is an apocalyptic number.

It is an amenable number.

1981961992 is a deficient number, since it is larger than the sum of its proper divisors (1769238008).

1981961992 is a wasteful number, since it uses less digits than its factorization.

1981961992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5653 (or 5649 counting only the distinct ones).

The product of its digits is 629856, while the sum is 55.

The square root of 1981961992 is about 44519.2317094534. The cubic root of 1981961992 is about 1256.1218609365.

The spelling of 1981961992 in words is "one billion, nine hundred eighty-one million, nine hundred sixty-one thousand, nine hundred ninety-two".