161981042688 has 156 divisors (see below), whose sum is σ = 468655109260. Its totient is φ = 53905195008.

The previous prime is 161981042651. The next prime is 161981042719. The reversal of 161981042688 is 886240189161.

It is a happy number.

161981042688 is a `hidden beast` number, since 1 + 61 + 9 + 81 + 0 + 426 + 88 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 31133896704 + 130847145984 = 176448^2 + 361728^2 .

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, 24806208 + ... + 24812736.

Almost surely, 2^161981042688 is an apocalyptic number.

161981042688 is a gapful number since it is divisible by the number (18) 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 161981042688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (234327554630).

161981042688 is an abundant number, since it is smaller than the sum of its proper divisors (306674066572).

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

161981042688 is an equidigital number, since it uses as much as digits as its factorization.

161981042688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7232 (or 7207 counting only the distinct ones).

The product of its (nonzero) digits is 1327104, while the sum is 54.

The spelling of 161981042688 in words is "one hundred sixty-one billion, nine hundred eighty-one million, forty-two thousand, six hundred eighty-eight".