161851620 has 144 divisors (see below), whose sum is σ = 536505984. Its totient is φ = 35712000.

The previous prime is 161851607. The next prime is 161851631. The reversal of 161851620 is 26158161.

161851620 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

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 47 ways as a sum of consecutive naturals, for example, 403420 + ... + 403820.

It is an arithmetic number, because the mean of its divisors is an integer number (3725736).

Almost surely, 2^161851620 is an apocalyptic number.

161851620 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 161851620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (268252992).

161851620 is an abundant number, since it is smaller than the sum of its proper divisors (374654364).

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

161851620 is a wasteful number, since it uses less digits than its factorization.

161851620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 482 (or 449 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 161851620 is about 12722.0918091326. The cubic root of 161851620 is about 544.9696922236.

The spelling of 161851620 in words is "one hundred sixty-one million, eight hundred fifty-one thousand, six hundred twenty".