21782864 has 20 divisors (see below), whose sum is σ = 42283380. Its totient is φ = 10871040.

The previous prime is 21782861. The next prime is 21782869. The reversal of 21782864 is 46828712.

It can be written as a sum of positive squares in 2 ways, for example, as 8880400 + 12902464 = 2980^2 + 3592^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21782861) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11282 + ... + 13070.

It is an arithmetic number, because the mean of its divisors is an integer number (2114169).

Almost surely, 2^21782864 is an apocalyptic number.

It is an amenable number.

21782864 is a deficient number, since it is larger than the sum of its proper divisors (20500516).

21782864 is a wasteful number, since it uses less digits than its factorization.

21782864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2558 (or 2552 counting only the distinct ones).

The product of its digits is 43008, while the sum is 38.

The square root of 21782864 is about 4667.2115872328. The cubic root of 21782864 is about 279.2790295242.

The spelling of 21782864 in words is "twenty-one million, seven hundred eighty-two thousand, eight hundred sixty-four".