21638230 has 8 divisors (see below), whose sum is σ = 38948832. Its totient is φ = 8655288.

The previous prime is 21638219. The next prime is 21638231. The reversal of 21638230 is 3283612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21638195 and 21638204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21638231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1081902 + ... + 1081921.

It is an arithmetic number, because the mean of its divisors is an integer number (4868604).

Almost surely, 2^21638230 is an apocalyptic number.

21638230 is a deficient number, since it is larger than the sum of its proper divisors (17310602).

21638230 is a wasteful number, since it uses less digits than its factorization.

21638230 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2163830.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 21638230 is about 4651.6910903455. The cubic root of 21638230 is about 278.6595368271.

The spelling of 21638230 in words is "twenty-one million, six hundred thirty-eight thousand, two hundred thirty".