161909687940 has 768 divisors, whose sum is σ = 632333205504. Its totient is φ = 29872281600.

The previous prime is 161909687903. The next prime is 161909688001. The reversal of 161909687940 is 49786909161.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (60).

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 183362739 + ... + 183363621.

It is an arithmetic number, because the mean of its divisors is an integer number (823350528).

Almost surely, 2^161909687940 is an apocalyptic number.

161909687940 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 161909687940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (316166602752).

161909687940 is an abundant number, since it is smaller than the sum of its proper divisors (470423517564).

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

161909687940 is a wasteful number, since it uses less digits than its factorization.

161909687940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1040 (or 1038 counting only the distinct ones).

The product of its (nonzero) digits is 5878656, while the sum is 60.

The spelling of 161909687940 in words is "one hundred sixty-one billion, nine hundred nine million, six hundred eighty-seven thousand, nine hundred forty".