16729921 has 24 divisors (see below), whose sum is σ = 19719224. Its totient is φ = 14100480.

The previous prime is 16729919. The next prime is 16729939. The reversal of 16729921 is 12992761.

It can be written as a sum of positive squares in 12 ways, for example, as 4730625 + 11999296 = 2175^2 + 3464^2 .

It is not a de Polignac number, because 16729921 - 2¹ = 16729919 is a prime.

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16729961) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 229141 + ... + 229213.

Almost surely, 2^16729921 is an apocalyptic number.

It is an amenable number.

16729921 is a deficient number, since it is larger than the sum of its proper divisors (2989303).

16729921 is a wasteful number, since it uses less digits than its factorization.

16729921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181 (or 164 counting only the distinct ones).

The product of its digits is 13608, while the sum is 37.

The square root of 16729921 is about 4090.2226100788. Note that the first 3 decimals coincide. The cubic root of 16729921 is about 255.7592187943.

The spelling of 16729921 in words is "sixteen million, seven hundred twenty-nine thousand, nine hundred twenty-one".