21247568 has 10 divisors (see below), whose sum is σ = 41167194. Its totient is φ = 10623776.

The previous prime is 21247543. The next prime is 21247573. The reversal of 21247568 is 86574212.

It can be written as a sum of positive squares in only one way, i.e., 19430464 + 1817104 = 4408^2 + 1348^2 .

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, 663971 + ... + 664002.

Almost surely, 2^21247568 is an apocalyptic number.

It is an amenable number.

21247568 is a deficient number, since it is larger than the sum of its proper divisors (19919626).

21247568 is a wasteful number, since it uses less digits than its factorization.

21247568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1327981 (or 1327975 counting only the distinct ones).

The product of its digits is 26880, while the sum is 35.

The square root of 21247568 is about 4609.5084336619. The cubic root of 21247568 is about 276.9723458080.

The spelling of 21247568 in words is "twenty-one million, two hundred forty-seven thousand, five hundred sixty-eight".