21166646 has 8 divisors (see below), whose sum is σ = 33421080. Its totient is φ = 10026288.

The previous prime is 21166643. The next prime is 21166679. The reversal of 21166646 is 64666112.

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

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21166643) 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 3 ways as a sum of consecutive naturals, for example, 278471 + ... + 278546.

It is an arithmetic number, because the mean of its divisors is an integer number (4177635).

Almost surely, 2^21166646 is an apocalyptic number.

21166646 is a deficient number, since it is larger than the sum of its proper divisors (12254434).

21166646 is a wasteful number, since it uses less digits than its factorization.

21166646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 557038.

The product of its digits is 10368, while the sum is 32.

The square root of 21166646 is about 4600.7223345905. The cubic root of 21166646 is about 276.6202793150.

It can be divided in two parts, 21166 and 646, that added together give a palindrome (21812).

The spelling of 21166646 in words is "twenty-one million, one hundred sixty-six thousand, six hundred forty-six".