21641166 has 24 divisors (see below), whose sum is σ = 46977840. Its totient is φ = 7200096.

The previous prime is 21641159. The next prime is 21641167. The reversal of 21641166 is 66114612.

21641166 is a `hidden beast` number, since 2 + 1 + 641 + 16 + 6 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21641167) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14386 + ... + 15818.

It is an arithmetic number, because the mean of its divisors is an integer number (1957410).

Almost surely, 2^21641166 is an apocalyptic number.

21641166 is an abundant number, since it is smaller than the sum of its proper divisors (25336674).

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

21641166 is a wasteful number, since it uses less digits than its factorization.

21641166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2280 (or 2277 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 21641166 is about 4652.0066637957. The cubic root of 21641166 is about 278.6721396354.

Adding to 21641166 its reverse (66114612), we get a palindrome (87755778).

The spelling of 21641166 in words is "twenty-one million, six hundred forty-one thousand, one hundred sixty-six".