21066606 has 24 divisors (see below), whose sum is σ = 49794264. Its totient is φ = 6383760.

The previous prime is 21066601. The next prime is 21066607. The reversal of 21066606 is 60666012.

It is a super-4 number, since 4×21066606⁴ (a number of 30 digits) contains 4444 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21066606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21066601) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 53001 + ... + 53396.

It is an arithmetic number, because the mean of its divisors is an integer number (2074761).

Almost surely, 2^21066606 is an apocalyptic number.

21066606 is an abundant number, since it is smaller than the sum of its proper divisors (28727658).

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

21066606 is a wasteful number, since it uses less digits than its factorization.

21066606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106416 (or 106413 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 21066606 is about 4589.8372520167. The cubic root of 21066606 is about 276.1837937751.

The spelling of 21066606 in words is "twenty-one million, sixty-six thousand, six hundred six".