16421391 has 24 divisors (see below), whose sum is σ = 27235104. Its totient is φ = 9339840.

The previous prime is 16421387. The next prime is 16421417. The reversal of 16421391 is 19312461.

16421391 is a `hidden beast` number, since 1 + 642 + 13 + 9 + 1 = 666.

It is not a de Polignac number, because 16421391 - 2² = 16421387 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16421341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16981 + ... + 17921.

It is an arithmetic number, because the mean of its divisors is an integer number (1134796).

Almost surely, 2^16421391 is an apocalyptic number.

16421391 is a deficient number, since it is larger than the sum of its proper divisors (10813713).

16421391 is a wasteful number, since it uses less digits than its factorization.

16421391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1231 (or 1228 counting only the distinct ones).

The product of its digits is 1296, while the sum is 27.

The square root of 16421391 is about 4052.3315510950. The cubic root of 16421391 is about 254.1772328254.

The spelling of 16421391 in words is "sixteen million, four hundred twenty-one thousand, three hundred ninety-one".