161781732 has 144 divisors (see below), whose sum is σ = 513912000. Its totient is φ = 43763328.

The previous prime is 161781731. The next prime is 161781743. The reversal of 161781732 is 237187161.

161781732 is a `hidden beast` number, since 1 + 617 + 8 + 1 + 7 + 32 = 666.

161781732 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (161781731) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 99744 + ... + 101352.

Almost surely, 2^161781732 is an apocalyptic number.

161781732 is a gapful number since it is divisible by the number (12) 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 161781732, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (256956000).

161781732 is an abundant number, since it is smaller than the sum of its proper divisors (352130268).

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

161781732 is a wasteful number, since it uses less digits than its factorization.

161781732 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1655 (or 1640 counting only the distinct ones).

The product of its digits is 14112, while the sum is 36.

The square root of 161781732 is about 12719.3447944460. The cubic root of 161781732 is about 544.8912410983.

The spelling of 161781732 in words is "one hundred sixty-one million, seven hundred eighty-one thousand, seven hundred thirty-two".