21556630 has 16 divisors (see below), whose sum is σ = 38867760. Its totient is φ = 8608032.

The previous prime is 21556627. The next prime is 21556643. The reversal of 21556630 is 3665512.

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, 5932 + ... + 8848.

It is an arithmetic number, because the mean of its divisors is an integer number (2429235).

Almost surely, 2^21556630 is an apocalyptic number.

21556630 is a deficient number, since it is larger than the sum of its proper divisors (17311130).

21556630 is a wasteful number, since it uses less digits than its factorization.

21556630 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3663.

The product of its (nonzero) digits is 5400, while the sum is 28.

The square root of 21556630 is about 4642.9118018761. The cubic root of 21556630 is about 278.3088109518.

The spelling of 21556630 in words is "twenty-one million, five hundred fifty-six thousand, six hundred thirty".