161351820 has 144 divisors (see below), whose sum is σ = 574636608. Its totient is φ = 35873280.

The previous prime is 161351791. The next prime is 161351833. The reversal of 161351820 is 28153161.

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 47 ways as a sum of consecutive naturals, for example, 44890 + ... + 48350.

It is an arithmetic number, because the mean of its divisors is an integer number (3990532).

Almost surely, 2^161351820 is an apocalyptic number.

161351820 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 161351820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (287318304).

161351820 is an abundant number, since it is smaller than the sum of its proper divisors (413284788).

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

161351820 is a wasteful number, since it uses less digits than its factorization.

161351820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3520 (or 3515 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 161351820 is about 12702.4336250972. The cubic root of 161351820 is about 544.4081558796.

It can be divided in two parts, 16135 and 1820, that added together give a triangular number (17955 = T₁₈₉).

The spelling of 161351820 in words is "one hundred sixty-one million, three hundred fifty-one thousand, eight hundred twenty".