21663448 has 8 divisors (see below), whose sum is σ = 40618980. Its totient is φ = 10831720.

The previous prime is 21663437. The next prime is 21663497. The reversal of 21663448 is 84436612.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1353958 + ... + 1353973.

Almost surely, 2^21663448 is an apocalyptic number.

It is an amenable number.

21663448 is a deficient number, since it is larger than the sum of its proper divisors (18955532).

21663448 is a wasteful number, since it uses less digits than its factorization.

21663448 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2707937 (or 2707933 counting only the distinct ones).

The product of its digits is 27648, while the sum is 34.

The square root of 21663448 is about 4654.4009281539. The cubic root of 21663448 is about 278.7677482047.

The spelling of 21663448 in words is "twenty-one million, six hundred sixty-three thousand, four hundred forty-eight".