161438728320 has 640 divisors, whose sum is σ = 593743011840. Its totient is φ = 41781436416.

The previous prime is 161438728261. The next prime is 161438728331. The reversal of 161438728320 is 23827834161.

161438728320 is a `hidden beast` number, since 1 + 614 + 3 + 8 + 7 + 2 + 8 + 3 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (640).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 421510849 + ... + 421511231.

It is an arithmetic number, because the mean of its divisors is an integer number (927723456).

Almost surely, 2^161438728320 is an apocalyptic number.

161438728320 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 161438728320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (296871505920).

161438728320 is an abundant number, since it is smaller than the sum of its proper divisors (432304283520).

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

161438728320 is a wasteful number, since it uses less digits than its factorization.

161438728320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 634 (or 613 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 45.

The spelling of 161438728320 in words is "one hundred sixty-one billion, four hundred thirty-eight million, seven hundred twenty-eight thousand, three hundred twenty".