1981801981836 has 36 divisors (see below), whose sum is σ = 5042730884464. Its totient is φ = 656225820000.

The previous prime is 1981801981777. The next prime is 1981801981847. The reversal of 1981801981836 is 6381891081891.

1981801981836 is a `hidden beast` number, since 1 + 98 + 180 + 198 + 183 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 182279515 + ... + 182290386.

Almost surely, 2^{1981801981836} is an apocalyptic number.

It is an amenable number.

1981801981836 is an abundant number, since it is smaller than the sum of its proper divisors (3060928902628).

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

1981801981836 is a wasteful number, since it uses less digits than its factorization.

1981801981836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 364570062 (or 364570057 counting only the distinct ones).

The product of its (nonzero) digits is 5971968, while the sum is 63.

The spelling of 1981801981836 in words is "one trillion, nine hundred eighty-one billion, eight hundred one million, nine hundred eighty-one thousand, eight hundred thirty-six".