21768775 has 24 divisors (see below), whose sum is σ = 32478080. Its totient is φ = 14139360.

The previous prime is 21768757. The next prime is 21768779. The reversal of 21768775 is 57786712.

It is a de Polignac number, because none of the positive numbers 2^k-21768775 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21768779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 52 + ... + 6598.

Almost surely, 2^21768775 is an apocalyptic number.

21768775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21768775 is a deficient number, since it is larger than the sum of its proper divisors (10709305).

21768775 is a wasteful number, since it uses less digits than its factorization.

21768775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6583 (or 6578 counting only the distinct ones).

The product of its digits is 164640, while the sum is 43.

The square root of 21768775 is about 4665.7019836248. The cubic root of 21768775 is about 279.2188046477.

The spelling of 21768775 in words is "twenty-one million, seven hundred sixty-eight thousand, seven hundred seventy-five".