16719921 has 27 divisors (see below), whose sum is σ = 25556011. Its totient is φ = 10533264.

The previous prime is 16719907. The next prime is 16719947. The reversal of 16719921 is 12991761.

The square root of 16719921 is 4089.

It is a perfect power (a square), and thus also a powerful number.

16719921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 8767521 + 7952400 = 2961^2 + 2820^2 .

It is not a de Polignac number, because 16719921 - 2⁵ = 16719889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16719421) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 355720 + ... + 355766.

Almost surely, 2^16719921 is an apocalyptic number.

16719921 is the 4089-th square number.

16719921 is the 2045-th centered octagonal number.

It is an amenable number.

16719921 is a deficient number, since it is larger than the sum of its proper divisors (8836090).

16719921 is an equidigital number, since it uses as much as digits as its factorization.

16719921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158 (or 79 counting only the distinct ones).

The product of its digits is 6804, while the sum is 36.

The cubic root of 16719921 is about 255.7082501945.

Multiplying 16719921 by its sum of digits (36), we get a square (601917156 = 24534²).

The spelling of 16719921 in words is "sixteen million, seven hundred nineteen thousand, nine hundred twenty-one".