161581000 has 128 divisors (see below), whose sum is σ = 443439360. Its totient is φ = 53952000.

The previous prime is 161580977. The next prime is 161581027. The reversal of 161581000 is 185161.

It is a super-2 number, since 2×161581000² = 52216839122000000, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 286719 + ... + 287281.

It is an arithmetic number, because the mean of its divisors is an integer number (3464370).

Almost surely, 2^161581000 is an apocalyptic number.

161581000 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 161581000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (221719680).

161581000 is an abundant number, since it is smaller than the sum of its proper divisors (281858360).

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

161581000 is a wasteful number, since it uses less digits than its factorization.

161581000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 632 (or 618 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 22.

The square root of 161581000 is about 12711.4515300181. The cubic root of 161581000 is about 544.6657884152.

The spelling of 161581000 in words is "one hundred sixty-one million, five hundred eighty-one thousand".