1638667 has 4 divisors (see below), whose sum is σ = 1641240. Its totient is φ = 1636096.

The previous prime is 1638653. The next prime is 1638673. The reversal of 1638667 is 7668361.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1638667 - 2¹¹ = 1636619 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1638677) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 459 + ... + 1867.

It is an arithmetic number, because the mean of its divisors is an integer number (410310).

2^1638667 is an apocalyptic number.

1638667 is a deficient number, since it is larger than the sum of its proper divisors (2573).

1638667 is a wasteful number, since it uses less digits than its factorization.

1638667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2572.

The product of its digits is 36288, while the sum is 37.

The square root of 1638667 is about 1280.1042926262. The cubic root of 1638667 is about 117.8954114915.

It can be divided in two parts, 16 and 38667, that added together give a palindrome (38683).

The spelling of 1638667 in words is "one million, six hundred thirty-eight thousand, six hundred sixty-seven".