161861720 has 16 divisors (see below), whose sum is σ = 364188960. Its totient is φ = 64744672.

The previous prime is 161861699. The next prime is 161861737. The reversal of 161861720 is 27168161.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2023232 + ... + 2023311.

It is an arithmetic number, because the mean of its divisors is an integer number (22761810).

Almost surely, 2^161861720 is an apocalyptic number.

161861720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161861720 is an abundant number, since it is smaller than the sum of its proper divisors (202327240).

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

161861720 is a wasteful number, since it uses less digits than its factorization.

161861720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4046554 (or 4046550 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 161861720 is about 12722.4887502407. The cubic root of 161861720 is about 544.9810278725.

The spelling of 161861720 in words is "one hundred sixty-one million, eight hundred sixty-one thousand, seven hundred twenty".