161905770 has 128 divisors (see below), whose sum is σ = 469324800. Its totient is φ = 39481344.

The previous prime is 161905729. The next prime is 161905771. The reversal of 161905770 is 77509161.

It is not an unprimeable number, because it can be changed into a prime (161905771) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 677311 + ... + 677549.

It is an arithmetic number, because the mean of its divisors is an integer number (3666600).

Almost surely, 2^161905770 is an apocalyptic number.

161905770 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 161905770, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (234662400).

161905770 is an abundant number, since it is smaller than the sum of its proper divisors (307419030).

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

161905770 is a wasteful number, since it uses less digits than its factorization.

161905770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 461 (or 455 counting only the distinct ones).

The product of its (nonzero) digits is 13230, while the sum is 36.

The square root of 161905770 is about 12724.2198189123. The cubic root of 161905770 is about 545.0304615020.

The spelling of 161905770 in words is "one hundred sixty-one million, nine hundred five thousand, seven hundred seventy".