21081066 has 8 divisors (see below), whose sum is σ = 42162144. Its totient is φ = 7027020.

The previous prime is 21081061. The next prime is 21081101. The reversal of 21081066 is 66018012.

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

21081066 is an admirable number.

It is a super-2 number, since 2×21081066² = 888822687392712, which contains 22 as substring.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21081061) 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, 1756750 + ... + 1756761.

It is an arithmetic number, because the mean of its divisors is an integer number (5270268).

Almost surely, 2^21081066 is an apocalyptic number.

21081066 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.

21081066 is a wasteful number, since it uses less digits than its factorization.

21081066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3513516.

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 21081066 is about 4591.4122010554. The cubic root of 21081066 is about 276.2469696575.

Adding to 21081066 its reverse (66018012), we get a palindrome (87099078).

The spelling of 21081066 in words is "twenty-one million, eighty-one thousand, sixty-six".