21864236 has 6 divisors (see below), whose sum is σ = 38262420. Its totient is φ = 10932116.

The previous prime is 21864229. The next prime is 21864239. The reversal of 21864236 is 63246812.

It is not an unprimeable number, because it can be changed into a prime (21864239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2733026 + ... + 2733033.

It is an arithmetic number, because the mean of its divisors is an integer number (6377070).

Almost surely, 2^21864236 is an apocalyptic number.

It is an amenable number.

21864236 is a deficient number, since it is larger than the sum of its proper divisors (16398184).

21864236 is a wasteful number, since it uses less digits than its factorization.

21864236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5466063 (or 5466061 counting only the distinct ones).

The product of its digits is 13824, while the sum is 32.

The square root of 21864236 is about 4675.9208718711. The cubic root of 21864236 is about 279.6263553550.

The spelling of 21864236 in words is "twenty-one million, eight hundred sixty-four thousand, two hundred thirty-six".