21663076 has 6 divisors (see below), whose sum is σ = 37910390. Its totient is φ = 10831536.

The previous prime is 21663071. The next prime is 21663091. The reversal of 21663076 is 67036612.

It can be written as a sum of positive squares in only one way, i.e., 19589476 + 2073600 = 4426^2 + 1440^2 .

It is not an unprimeable number, because it can be changed into a prime (21663071) by changing a digit.

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 as a sum of consecutive naturals, namely, 2707881 + ... + 2707888.

Almost surely, 2^21663076 is an apocalyptic number.

It is an amenable number.

21663076 is a deficient number, since it is larger than the sum of its proper divisors (16247314).

21663076 is a wasteful number, since it uses less digits than its factorization.

21663076 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5415773 (or 5415771 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 31.

The square root of 21663076 is about 4654.3609658040. The cubic root of 21663076 is about 278.7661525492.

Adding to 21663076 its reverse (67036612), we get a palindrome (88699688).

The spelling of 21663076 in words is "twenty-one million, six hundred sixty-three thousand, seventy-six".