16391638 has 16 divisors (see below), whose sum is σ = 26278560. Its totient is φ = 7641216.

The previous prime is 16391633. The next prime is 16391657. The reversal of 16391638 is 83619361.

It is a junction number, because it is equal to n+sod(n) for n = 16391597 and 16391606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16391633) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1495 + ... + 5917.

It is an arithmetic number, because the mean of its divisors is an integer number (1642410).

Almost surely, 2^16391638 is an apocalyptic number.

16391638 is a deficient number, since it is larger than the sum of its proper divisors (9886922).

16391638 is a wasteful number, since it uses less digits than its factorization.

16391638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4551.

The product of its digits is 23328, while the sum is 37.

The square root of 16391638 is about 4048.6587902662. The cubic root of 16391638 is about 254.0236301822.

The spelling of 16391638 in words is "sixteen million, three hundred ninety-one thousand, six hundred thirty-eight".