161597721600 has 924 divisors, whose sum is σ = 686926593904. Its totient is φ = 36906762240.

The previous prime is 161597721557. The next prime is 161597721611. The reversal of 161597721600 is 6127795161.

161597721600 is a `hidden beast` number, since 1 + 6 + 15 + 9 + 7 + 7 + 21 + 600 = 666.

It is a super-2 number, since 2×161597721600² (a number of 23 digits) contains 22 as substring.

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 83 ways as a sum of consecutive naturals, for example, 130636182 + ... + 130637418.

Almost surely, 2^161597721600 is an apocalyptic number.

161597721600 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 161597721600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (343463296952).

161597721600 is an abundant number, since it is smaller than the sum of its proper divisors (525328872304).

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

161597721600 is an equidigital number, since it uses as much as digits as its factorization.

161597721600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1292 (or 1254 counting only the distinct ones).

The product of its (nonzero) digits is 158760, while the sum is 45.

The spelling of 161597721600 in words is "one hundred sixty-one billion, five hundred ninety-seven million, seven hundred twenty-one thousand, six hundred".