21864786 has 16 divisors (see below), whose sum is σ = 43775424. Its totient is φ = 7280624.

The previous prime is 21864761. The next prime is 21864797. The reversal of 21864786 is 68746812.

It is a Curzon number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 10096 + ... + 12068.

It is an arithmetic number, because the mean of its divisors is an integer number (2735964).

Almost surely, 2^21864786 is an apocalyptic number.

21864786 is an abundant number, since it is smaller than the sum of its proper divisors (21910638).

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

21864786 is a wasteful number, since it uses less digits than its factorization.

21864786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3825.

The product of its digits is 129024, while the sum is 42.

The square root of 21864786 is about 4675.9796834460. The cubic root of 21864786 is about 279.6287000243.

The spelling of 21864786 in words is "twenty-one million, eight hundred sixty-four thousand, seven hundred eighty-six".