161843778 has 64 divisors (see below), whose sum is σ = 377395200. Its totient is φ = 51313680.

The previous prime is 161843761. The next prime is 161843779. The reversal of 161843778 is 877348161.

It is not an unprimeable number, because it can be changed into a prime (161843779) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 386053 + ... + 386471.

It is an arithmetic number, because the mean of its divisors is an integer number (5896800).

Almost surely, 2^161843778 is an apocalyptic number.

161843778 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 161843778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (188697600).

161843778 is an abundant number, since it is smaller than the sum of its proper divisors (215551422).

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

161843778 is a wasteful number, since it uses less digits than its factorization.

161843778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 764 (or 758 counting only the distinct ones).

The product of its digits is 225792, while the sum is 45.

The square root of 161843778 is about 12721.7836013666. The cubic root of 161843778 is about 544.9608904966.

The spelling of 161843778 in words is "one hundred sixty-one million, eight hundred forty-three thousand, seven hundred seventy-eight".