21066646 has 16 divisors (see below), whose sum is σ = 32465664. Its totient is φ = 10246824.

The previous prime is 21066641. The next prime is 21066677. The reversal of 21066646 is 64666012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21066641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41631 + ... + 42133.

It is an arithmetic number, because the mean of its divisors is an integer number (2029104).

Almost surely, 2^21066646 is an apocalyptic number.

21066646 is a deficient number, since it is larger than the sum of its proper divisors (11399018).

21066646 is a wasteful number, since it uses less digits than its factorization.

21066646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1035.

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 21066646 is about 4589.8416094676. The cubic root of 21066646 is about 276.1839685753.

It can be divided in two parts, 21066 and 646, that added together give a palindrome (21712).

The spelling of 21066646 in words is "twenty-one million, sixty-six thousand, six hundred forty-six".