21585966 has 16 divisors (see below), whose sum is σ = 43576704. Its totient is φ = 7127864.

The previous prime is 21585961. The next prime is 21585973. The reversal of 21585966 is 66958512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21585961) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16170 + ... + 17453.

It is an arithmetic number, because the mean of its divisors is an integer number (2723544).

Almost surely, 2^21585966 is an apocalyptic number.

21585966 is an abundant number, since it is smaller than the sum of its proper divisors (21990738).

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

21585966 is a wasteful number, since it uses less digits than its factorization.

21585966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33735.

The product of its digits is 129600, while the sum is 42.

The square root of 21585966 is about 4646.0699521208. The cubic root of 21585966 is about 278.4350020812.

The spelling of 21585966 in words is "twenty-one million, five hundred eighty-five thousand, nine hundred sixty-six".