21435638 has 24 divisors (see below), whose sum is σ = 38117952. Its totient is φ = 9011184.

The previous prime is 21435593. The next prime is 21435643. The reversal of 21435638 is 83653412.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 3131 + ... + 7257.

It is an arithmetic number, because the mean of its divisors is an integer number (1588248).

Almost surely, 2^21435638 is an apocalyptic number.

21435638 is a deficient number, since it is larger than the sum of its proper divisors (16682314).

21435638 is a wasteful number, since it uses less digits than its factorization.

21435638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4196 (or 4189 counting only the distinct ones).

The product of its digits is 17280, while the sum is 32.

The square root of 21435638 is about 4629.8637128970. The cubic root of 21435638 is about 277.7871410296.

The spelling of 21435638 in words is "twenty-one million, four hundred thirty-five thousand, six hundred thirty-eight".