21195566 has 16 divisors (see below), whose sum is σ = 38473056. Its totient is φ = 8549376.

The previous prime is 21195563. The next prime is 21195589. The reversal of 21195566 is 66559112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21195563) 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 7 ways as a sum of consecutive naturals, for example, 44291 + ... + 44766.

It is an arithmetic number, because the mean of its divisors is an integer number (2404566).

Almost surely, 2^21195566 is an apocalyptic number.

21195566 is a deficient number, since it is larger than the sum of its proper divisors (17277490).

21195566 is a wasteful number, since it uses less digits than its factorization.

21195566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89083.

The product of its digits is 16200, while the sum is 35.

The square root of 21195566 is about 4603.8642464782. The cubic root of 21195566 is about 276.7462041283.

The spelling of 21195566 in words is "twenty-one million, one hundred ninety-five thousand, five hundred sixty-six".