21725666 has 8 divisors (see below), whose sum is σ = 32678400. Its totient is φ = 10832868.

The previous prime is 21725663. The next prime is 21725689. The reversal of 21725666 is 66652712.

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21725663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14066 + ... + 15533.

It is an arithmetic number, because the mean of its divisors is an integer number (4084800).

Almost surely, 2^21725666 is an apocalyptic number.

21725666 is a deficient number, since it is larger than the sum of its proper divisors (10952734).

21725666 is a wasteful number, since it uses less digits than its factorization.

21725666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29968.

The product of its digits is 30240, while the sum is 35.

The square root of 21725666 is about 4661.0799177873. The cubic root of 21725666 is about 279.0343692538.

The spelling of 21725666 in words is "twenty-one million, seven hundred twenty-five thousand, six hundred sixty-six".