161906921280 has 840 divisors, whose sum is σ = 651161503872. Its totient is φ = 38097506304.

The previous prime is 161906921251. The next prime is 161906921329. The reversal of 161906921280 is 82129609161.

161906921280 is a `hidden beast` number, since 1 + 619 + 0 + 6 + 9 + 2 + 1 + 28 + 0 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 100750237 + ... + 100751843.

Almost surely, 2^161906921280 is an apocalyptic number.

161906921280 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 161906921280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (325580751936).

161906921280 is an abundant number, since it is smaller than the sum of its proper divisors (489254582592).

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

161906921280 is a wasteful number, since it uses less digits than its factorization.

161906921280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1685 (or 1653 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 45.

The spelling of 161906921280 in words is "one hundred sixty-one billion, nine hundred six million, nine hundred twenty-one thousand, two hundred eighty".