161561646 has 48 divisors (see below), whose sum is σ = 364116480. Its totient is φ = 51716880.

The previous prime is 161561623. The next prime is 161561663. The reversal of 161561646 is 646165161.

It is a happy number.

161561646 is a `hidden beast` number, since 1 + 6 + 1 + 5 + 6 + 1 + 646 = 666.

It is a super-2 number, since 2×161561646² = 52204330916458632, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161561646.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 76521 + ... + 78603.

It is an arithmetic number, because the mean of its divisors is an integer number (7585760).

Almost surely, 2^161561646 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161561646, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (182058240).

161561646 is an abundant number, since it is smaller than the sum of its proper divisors (202554834).

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

161561646 is a wasteful number, since it uses less digits than its factorization.

161561646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2261 (or 2258 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 161561646 is about 12710.6902251609. The cubic root of 161561646 is about 544.6440410510.

The spelling of 161561646 in words is "one hundred sixty-one million, five hundred sixty-one thousand, six hundred forty-six".