21216670 has 8 divisors (see below), whose sum is σ = 38190024. Its totient is φ = 8486664.

The previous prime is 21216659. The next prime is 21216707. The reversal of 21216670 is 7661212.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1060824 + ... + 1060843.

It is an arithmetic number, because the mean of its divisors is an integer number (4773753).

Almost surely, 2^21216670 is an apocalyptic number.

21216670 is a deficient number, since it is larger than the sum of its proper divisors (16973354).

21216670 is a wasteful number, since it uses less digits than its factorization.

21216670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2121674.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21216670 is about 4606.1556638915. The cubic root of 21216670 is about 276.8380238759.

Adding to 21216670 its reverse (7661212), we get a palindrome (28877882).

The spelling of 21216670 in words is "twenty-one million, two hundred sixteen thousand, six hundred seventy".