16328721 has 16 divisors (see below), whose sum is σ = 23143104. Its totient is φ = 10205184.

The previous prime is 16328699. The next prime is 16328737. The reversal of 16328721 is 12782361.

It is not a de Polignac number, because 16328721 - 2¹⁰ = 16327697 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16320721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17550 + ... + 18456.

It is an arithmetic number, because the mean of its divisors is an integer number (1446444).

Almost surely, 2^16328721 is an apocalyptic number.

It is an amenable number.

16328721 is a deficient number, since it is larger than the sum of its proper divisors (6814383).

16328721 is a wasteful number, since it uses less digits than its factorization.

16328721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1280.

The product of its digits is 4032, while the sum is 30.

The square root of 16328721 is about 4040.8812157746. The cubic root of 16328721 is about 253.6982021154.

The spelling of 16328721 in words is "sixteen million, three hundred twenty-eight thousand, seven hundred twenty-one".