21864616 has 8 divisors (see below), whose sum is σ = 40996170. Its totient is φ = 10932304.

The previous prime is 21864613. The next prime is 21864617. The reversal of 21864616 is 61646812.

It can be written as a sum of positive squares in only one way, i.e., 21436900 + 427716 = 4630^2 + 654^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×21864616² = 956122865654912, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21864613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1366531 + ... + 1366546.

Almost surely, 2^21864616 is an apocalyptic number.

It is an amenable number.

21864616 is a deficient number, since it is larger than the sum of its proper divisors (19131554).

21864616 is a wasteful number, since it uses less digits than its factorization.

21864616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2733083 (or 2733079 counting only the distinct ones).

The product of its digits is 13824, while the sum is 34.

The square root of 21864616 is about 4675.9615054019. The cubic root of 21864616 is about 279.6279753125.

The spelling of 21864616 in words is "twenty-one million, eight hundred sixty-four thousand, six hundred sixteen".