21678268 has 6 divisors (see below), whose sum is σ = 37936976. Its totient is φ = 10839132.

The previous prime is 21678257. The next prime is 21678277. The reversal of 21678268 is 86287612.

It is a self number, because there is not a number n which added to its sum of digits gives 21678268.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2709780 + ... + 2709787.

Almost surely, 2^21678268 is an apocalyptic number.

It is an amenable number.

21678268 is a deficient number, since it is larger than the sum of its proper divisors (16258708).

21678268 is a wasteful number, since it uses less digits than its factorization.

21678268 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5419571 (or 5419569 counting only the distinct ones).

The product of its digits is 64512, while the sum is 40.

The square root of 21678268 is about 4655.9926975888. The cubic root of 21678268 is about 278.8313022043.

The spelling of 21678268 in words is "twenty-one million, six hundred seventy-eight thousand, two hundred sixty-eight".