161720800 has 72 divisors (see below), whose sum is σ = 407598912. Its totient is φ = 62592000.

The previous prime is 161720789. The next prime is 161720809. The reversal of 161720800 is 8027161.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161720809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21540 + ... + 28060.

It is an arithmetic number, because the mean of its divisors is an integer number (5661096).

Almost surely, 2^161720800 is an apocalyptic number.

161720800 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 161720800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (203799456).

161720800 is an abundant number, since it is smaller than the sum of its proper divisors (245878112).

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

161720800 is a wasteful number, since it uses less digits than its factorization.

161720800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6572 (or 6559 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 161720800 is about 12716.9493197071. The cubic root of 161720800 is about 544.8228248815.

Adding to 161720800 its reverse (8027161), we get a palindrome (169747961).

The spelling of 161720800 in words is "one hundred sixty-one million, seven hundred twenty thousand, eight hundred".