21806230 has 16 divisors (see below), whose sum is σ = 39805344. Its totient is φ = 8599360.

The previous prime is 21806227. The next prime is 21806263. The reversal of 21806230 is 3260812.

21806230 = 208² + 209² + ... + 420².

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 7 ways as a sum of consecutive naturals, for example, 14647 + ... + 16066.

It is an arithmetic number, because the mean of its divisors is an integer number (2487834).

Almost surely, 2^21806230 is an apocalyptic number.

21806230 is a deficient number, since it is larger than the sum of its proper divisors (17999114).

21806230 is a wasteful number, since it uses less digits than its factorization.

21806230 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30791.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21806230 is about 4669.7141240123. The cubic root of 21806230 is about 279.3788526679.

The spelling of 21806230 in words is "twenty-one million, eight hundred six thousand, two hundred thirty".