21830638 has 4 divisors (see below), whose sum is σ = 32745960. Its totient is φ = 10915318.

The previous prime is 21830621. The next prime is 21830659. The reversal of 21830638 is 83603812.

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, 5457658 + ... + 5457661.

It is an arithmetic number, because the mean of its divisors is an integer number (8186490).

Almost surely, 2^21830638 is an apocalyptic number.

21830638 is a deficient number, since it is larger than the sum of its proper divisors (10915322).

21830638 is a wasteful number, since it uses less digits than its factorization.

21830638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10915321.

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

The square root of 21830638 is about 4672.3268293218. The cubic root of 21830638 is about 279.4830512752.

The spelling of 21830638 in words is "twenty-one million, eight hundred thirty thousand, six hundred thirty-eight".