161721768 has 64 divisors (see below), whose sum is σ = 458337600. Its totient is φ = 47139840.

The previous prime is 161721751. The next prime is 161721803. The reversal of 161721768 is 867127161.

161721768 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a hoax number, since the sum of its digits (39) 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 (39).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7713 + ... + 19568.

It is an arithmetic number, because the mean of its divisors is an integer number (7161525).

Almost surely, 2^161721768 is an apocalyptic number.

It is an amenable number.

161721768 is an abundant number, since it is smaller than the sum of its proper divisors (296615832).

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

161721768 is a wasteful number, since it uses less digits than its factorization.

161721768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27322 (or 27318 counting only the distinct ones).

The product of its digits is 28224, while the sum is 39.

The square root of 161721768 is about 12716.9873790926. The cubic root of 161721768 is about 544.8239119143.

The spelling of 161721768 in words is "one hundred sixty-one million, seven hundred twenty-one thousand, seven hundred sixty-eight".