161937780 has 48 divisors (see below), whose sum is σ = 456711360. Its totient is φ = 42870528.

The previous prime is 161937773. The next prime is 161937793. The reversal of 161937780 is 87739161.

161937780 = T₃₀₅ + T₃₀₆ + ... + T₉₉₉.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1369 + ... + 18048.

It is an arithmetic number, because the mean of its divisors is an integer number (9514820).

Almost surely, 2^161937780 is an apocalyptic number.

161937780 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 161937780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (228355680).

161937780 is an abundant number, since it is smaller than the sum of its proper divisors (294773580).

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

161937780 is a wasteful number, since it uses less digits than its factorization.

161937780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19568 (or 19566 counting only the distinct ones).

The product of its (nonzero) digits is 63504, while the sum is 42.

The square root of 161937780 is about 12725.4775941809. The cubic root of 161937780 is about 545.0663780219.

The spelling of 161937780 in words is "one hundred sixty-one million, nine hundred thirty-seven thousand, seven hundred eighty".