21663652 has 6 divisors (see below), whose sum is σ = 37911398. Its totient is φ = 10831824.

The previous prime is 21663647. The next prime is 21663659. The reversal of 21663652 is 25636612.

It can be written as a sum of positive squares in only one way, i.e., 18181696 + 3481956 = 4264^2 + 1866^2 .

It is not an unprimeable number, because it can be changed into a prime (21663659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2707953 + ... + 2707960.

Almost surely, 2^21663652 is an apocalyptic number.

It is an amenable number.

21663652 is a deficient number, since it is larger than the sum of its proper divisors (16247746).

21663652 is a wasteful number, since it uses less digits than its factorization.

21663652 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5415917 (or 5415915 counting only the distinct ones).

The product of its digits is 12960, while the sum is 31.

The square root of 21663652 is about 4654.4228428453. The cubic root of 21663652 is about 278.7686232338.

The spelling of 21663652 in words is "twenty-one million, six hundred sixty-three thousand, six hundred fifty-two".