21630666 has 8 divisors (see below), whose sum is σ = 43261344. Its totient is φ = 7210220.

The previous prime is 21630659. The next prime is 21630689. The reversal of 21630666 is 66603612.

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

21630666 is an admirable number.

It is an unprimeable number.

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, 1802550 + ... + 1802561.

It is an arithmetic number, because the mean of its divisors is an integer number (5407668).

Almost surely, 2^21630666 is an apocalyptic number.

21630666 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21630666 is a wasteful number, since it uses less digits than its factorization.

21630666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3605116.

The product of its (nonzero) digits is 7776, while the sum is 30.

The square root of 21630666 is about 4650.8779816288. The cubic root of 21630666 is about 278.6270630313.

The spelling of 21630666 in words is "twenty-one million, six hundred thirty thousand, six hundred sixty-six".