21268578 has 8 divisors (see below), whose sum is σ = 42537168. Its totient is φ = 7089524.

The previous prime is 21268567. The next prime is 21268579. The reversal of 21268578 is 87586212.

It is a sphenic number, since it is the product of 3 distinct primes.

21268578 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21268579) 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, 1772376 + ... + 1772387.

It is an arithmetic number, because the mean of its divisors is an integer number (5317146).

Almost surely, 2^21268578 is an apocalyptic number.

21268578 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21268578 is a wasteful number, since it uses less digits than its factorization.

21268578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3544768.

The product of its digits is 53760, while the sum is 39.

The square root of 21268578 is about 4611.7868554390. The cubic root of 21268578 is about 277.0636075781.

The spelling of 21268578 in words is "twenty-one million, two hundred sixty-eight thousand, five hundred seventy-eight".