161811640099968 has 128 divisors (see below), whose sum is σ = 434257566664320. Its totient is φ = 53379396304896.

The previous prime is 161811640099957. The next prime is 161811640099969. The reversal of 161811640099968 is 869990046118161.

It is a tau number, because it is divible by the number of its divisors (128).

It is not an unprimeable number, because it can be changed into a prime (161811640099969) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1616401405 + ... + 1616501507.

It is an arithmetic number, because the mean of its divisors is an integer number (3392637239565).

Almost surely, 2^{161811640099968} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161811640099968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (217128783332160).

161811640099968 is an abundant number, since it is smaller than the sum of its proper divisors (272445926564352).

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

161811640099968 is a wasteful number, since it uses less digits than its factorization.

161811640099968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143614 (or 143602 counting only the distinct ones).

The product of its (nonzero) digits is 40310784, while the sum is 69.

The spelling of 161811640099968 in words is "one hundred sixty-one trillion, eight hundred eleven billion, six hundred forty million, ninety-nine thousand, nine hundred sixty-eight".