16421997 has 16 divisors (see below), whose sum is σ = 22472640. Its totient is φ = 10662912.

The previous prime is 16421963. The next prime is 16422019. The reversal of 16421997 is 79912461.

It is a de Polignac number, because none of the positive numbers 2^k-16421997 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16421297) 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, 28173 + ... + 28749.

It is an arithmetic number, because the mean of its divisors is an integer number (1404540).

Almost surely, 2^16421997 is an apocalyptic number.

It is an amenable number.

16421997 is a deficient number, since it is larger than the sum of its proper divisors (6050643).

16421997 is a wasteful number, since it uses less digits than its factorization.

16421997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 812.

The product of its digits is 27216, while the sum is 39.

The square root of 16421997 is about 4052.4063221745. The cubic root of 16421997 is about 254.1803594283.

The spelling of 16421997 in words is "sixteen million, four hundred twenty-one thousand, nine hundred ninety-seven".