21767728 has 20 divisors (see below), whose sum is σ = 42868288. Its totient is φ = 10704960.

The previous prime is 21767717. The next prime is 21767731. The reversal of 21767728 is 82776712.

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, 10176 + ... + 12127.

Almost surely, 2^21767728 is an apocalyptic number.

It is an amenable number.

21767728 is a deficient number, since it is larger than the sum of its proper divisors (21100560).

21767728 is a wasteful number, since it uses less digits than its factorization.

21767728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22372 (or 22366 counting only the distinct ones).

The product of its digits is 65856, while the sum is 40.

The square root of 21767728 is about 4665.5897805101. The cubic root of 21767728 is about 279.2143281016.

The spelling of 21767728 in words is "twenty-one million, seven hundred sixty-seven thousand, seven hundred twenty-eight".