21670778 has 8 divisors (see below), whose sum is σ = 32542560. Its totient is φ = 10823260.

The previous prime is 21670777. The next prime is 21670787. The reversal of 21670778 is 87707612.

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

It is not an unprimeable number, because it can be changed into a prime (21670777) 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, 3638 + ... + 7521.

It is an arithmetic number, because the mean of its divisors is an integer number (4067820).

Almost surely, 2^21670778 is an apocalyptic number.

21670778 is a deficient number, since it is larger than the sum of its proper divisors (10871782).

21670778 is a wasteful number, since it uses less digits than its factorization.

21670778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12132.

The product of its (nonzero) digits is 32928, while the sum is 38.

The square root of 21670778 is about 4655.1882883510. The cubic root of 21670778 is about 278.7991857544.

The spelling of 21670778 in words is "twenty-one million, six hundred seventy thousand, seven hundred seventy-eight".