21668770 has 8 divisors (see below), whose sum is σ = 39003804. Its totient is φ = 8667504.

The previous prime is 21668749. The next prime is 21668789. The reversal of 21668770 is 7786612.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20729809 + 938961 = 4553^2 + 969^2 .

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1083429 + ... + 1083448.

Almost surely, 2^21668770 is an apocalyptic number.

21668770 is a deficient number, since it is larger than the sum of its proper divisors (17335034).

21668770 is a wasteful number, since it uses less digits than its factorization.

21668770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2166884.

The product of its (nonzero) digits is 28224, while the sum is 37.

The square root of 21668770 is about 4654.9726100161. The cubic root of 21668770 is about 278.7905743722.

It can be divided in two parts, 216 and 68770, that added together give a palindrome (68986).

The spelling of 21668770 in words is "twenty-one million, six hundred sixty-eight thousand, seven hundred seventy".