161861680 has 80 divisors (see below), whose sum is σ = 390153600. Its totient is φ = 62401536.

The previous prime is 161861671. The next prime is 161861681. The reversal of 161861680 is 86168161.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (37).

It is not an unprimeable number, because it can be changed into a prime (161861681) 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 15 ways as a sum of consecutive naturals, for example, 440857 + ... + 441223.

It is an arithmetic number, because the mean of its divisors is an integer number (4876920).

Almost surely, 2^161861680 is an apocalyptic number.

161861680 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 161861680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (195076800).

161861680 is an abundant number, since it is smaller than the sum of its proper divisors (228291920).

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

161861680 is a wasteful number, since it uses less digits than its factorization.

161861680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 566 (or 560 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 37.

The square root of 161861680 is about 12722.4871782211. The cubic root of 161861680 is about 544.9809829798.

The spelling of 161861680 in words is "one hundred sixty-one million, eight hundred sixty-one thousand, six hundred eighty".