161721672 has 64 divisors (see below), whose sum is σ = 474568320. Its totient is φ = 44955648.

The previous prime is 161721647. The next prime is 161721691. The reversal of 161721672 is 276127161.

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 6793 + ... + 19224.

It is an arithmetic number, because the mean of its divisors is an integer number (7415130).

Almost surely, 2^161721672 is an apocalyptic number.

161721672 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

161721672 is an abundant number, since it is smaller than the sum of its proper divisors (312846648).

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

161721672 is a wasteful number, since it uses less digits than its factorization.

161721672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26070 (or 26066 counting only the distinct ones).

The product of its digits is 7056, while the sum is 33.

The square root of 161721672 is about 12716.9836046132. The cubic root of 161721672 is about 544.8238041095.

The spelling of 161721672 in words is "one hundred sixty-one million, seven hundred twenty-one thousand, six hundred seventy-two".