21297784 has 32 divisors (see below), whose sum is σ = 42742800. Its totient is φ = 9918720.

The previous prime is 21297779. The next prime is 21297791. The reversal of 21297784 is 48779212.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8124 + ... + 10420.

Almost surely, 2^21297784 is an apocalyptic number.

It is an amenable number.

21297784 is an abundant number, since it is smaller than the sum of its proper divisors (21445016).

21297784 is a wasteful number, since it uses less digits than its factorization.

21297784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2383 (or 2379 counting only the distinct ones).

The product of its digits is 56448, while the sum is 40.

The square root of 21297784 is about 4614.9522207711. The cubic root of 21297784 is about 277.1903707716.

The spelling of 21297784 in words is "twenty-one million, two hundred ninety-seven thousand, seven hundred eighty-four".