21768255 has 24 divisors (see below), whose sum is σ = 38128272. Its totient is φ = 11487744.

The previous prime is 21768251. The next prime is 21768269. The reversal of 21768255 is 55286712.

It is a happy number.

It is not a de Polignac number, because 21768255 - 2² = 21768251 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21768251) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1872 + ... + 6858.

It is an arithmetic number, because the mean of its divisors is an integer number (1588678).

Almost surely, 2^21768255 is an apocalyptic number.

21768255 is a deficient number, since it is larger than the sum of its proper divisors (16360017).

21768255 is a wasteful number, since it uses less digits than its factorization.

21768255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5095 (or 5092 counting only the distinct ones).

The product of its digits is 33600, while the sum is 36.

The square root of 21768255 is about 4665.6462574867. The cubic root of 21768255 is about 279.2165813572.

The spelling of 21768255 in words is "twenty-one million, seven hundred sixty-eight thousand, two hundred fifty-five".