21779728 has 20 divisors (see below), whose sum is σ = 42362368. Its totient is φ = 10847520.

The previous prime is 21779713. The next prime is 21779731. The reversal of 21779728 is 82797712.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1825 + ... + 6847.

Almost surely, 2^21779728 is an apocalyptic number.

It is an amenable number.

21779728 is a deficient number, since it is larger than the sum of its proper divisors (20582640).

21779728 is a wasteful number, since it uses less digits than its factorization.

21779728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5302 (or 5296 counting only the distinct ones).

The product of its digits is 98784, while the sum is 43.

The square root of 21779728 is about 4666.8756143699. The cubic root of 21779728 is about 279.2656266176.

The spelling of 21779728 in words is "twenty-one million, seven hundred seventy-nine thousand, seven hundred twenty-eight".