21426666 has 8 divisors (see below), whose sum is σ = 42853344. Its totient is φ = 7142220.

The previous prime is 21426659. The next prime is 21426683. The reversal of 21426666 is 66662412.

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

21426666 is an admirable number.

21426666 is a modest number, since divided by 6666 gives 2142 as remainder.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1785550 + ... + 1785561.

It is an arithmetic number, because the mean of its divisors is an integer number (5356668).

Almost surely, 2^21426666 is an apocalyptic number.

21426666 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.

21426666 is a wasteful number, since it uses less digits than its factorization.

21426666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3571116.

The product of its digits is 20736, while the sum is 33.

The square root of 21426666 is about 4628.8946844792. The cubic root of 21426666 is about 277.7483791939.

The spelling of 21426666 in words is "twenty-one million, four hundred twenty-six thousand, six hundred sixty-six".