161432720 has 20 divisors (see below), whose sum is σ = 375331260. Its totient is φ = 64573056.

The previous prime is 161432671. The next prime is 161432723. The reversal of 161432720 is 27234161.

It can be written as a sum of positive squares in 2 ways, for example, as 93006736 + 68425984 = 9644^2 + 8272^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 161432720.

It is not an unprimeable number, because it can be changed into a prime (161432723) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1008875 + ... + 1009034.

It is an arithmetic number, because the mean of its divisors is an integer number (18766563).

Almost surely, 2^161432720 is an apocalyptic number.

161432720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161432720 is an abundant number, since it is smaller than the sum of its proper divisors (213898540).

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

161432720 is a wasteful number, since it uses less digits than its factorization.

161432720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2017922 (or 2017916 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 26.

The square root of 161432720 is about 12705.6176551949. The cubic root of 161432720 is about 544.4991273997.

Adding to 161432720 its reverse (27234161), we get a palindrome (188666881).

The spelling of 161432720 in words is "one hundred sixty-one million, four hundred thirty-two thousand, seven hundred twenty".