21504866 has 4 divisors (see below), whose sum is σ = 32257302. Its totient is φ = 10752432.

The previous prime is 21504841. The next prime is 21504871. The reversal of 21504866 is 66840512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 15768841 + 5736025 = 3971^2 + 2395^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5376215 + ... + 5376218.

Almost surely, 2^21504866 is an apocalyptic number.

21504866 is a deficient number, since it is larger than the sum of its proper divisors (10752436).

21504866 is a wasteful number, since it uses less digits than its factorization.

21504866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10752435.

The product of its (nonzero) digits is 11520, while the sum is 32.

The square root of 21504866 is about 4637.3339323366. Note that the first 3 decimals coincide. The cubic root of 21504866 is about 278.0858644762.

The spelling of 21504866 in words is "twenty-one million, five hundred four thousand, eight hundred sixty-six".