161099820 has 384 divisors, whose sum is σ = 638668800. Its totient is φ = 32845824.

The previous prime is 161099791. The next prime is 161099833. The reversal of 161099820 is 28990161.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 1477926 + ... + 1478034.

It is an arithmetic number, because the mean of its divisors is an integer number (1663200).

Almost surely, 2^161099820 is an apocalyptic number.

161099820 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 161099820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (319334400).

161099820 is an abundant number, since it is smaller than the sum of its proper divisors (477568980).

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

161099820 is a wasteful number, since it uses less digits than its factorization.

161099820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174 (or 166 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 161099820 is about 12692.5103899898. The cubic root of 161099820 is about 544.1245884985.

The spelling of 161099820 in words is "one hundred sixty-one million, ninety-nine thousand, eight hundred twenty".