16421638 has 4 divisors (see below), whose sum is σ = 24632460. Its totient is φ = 8210818.

The previous prime is 16421623. The next prime is 16421683. The reversal of 16421638 is 83612461.

It is a happy number.

16421638 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4105408 + ... + 4105411.

It is an arithmetic number, because the mean of its divisors is an integer number (6158115).

Almost surely, 2^16421638 is an apocalyptic number.

16421638 is a deficient number, since it is larger than the sum of its proper divisors (8210822).

16421638 is an equidigital number, since it uses as much as digits as its factorization.

16421638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8210821.

The product of its digits is 6912, while the sum is 31.

The square root of 16421638 is about 4052.3620272626. The cubic root of 16421638 is about 254.1785072091.

The spelling of 16421638 in words is "sixteen million, four hundred twenty-one thousand, six hundred thirty-eight".