21021670 has 8 divisors (see below), whose sum is σ = 37839024. Its totient is φ = 8408664.

The previous prime is 21021667. The next prime is 21021683. The reversal of 21021670 is 7612012.

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 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, 1051074 + ... + 1051093.

It is an arithmetic number, because the mean of its divisors is an integer number (4729878).

Almost surely, 2^21021670 is an apocalyptic number.

21021670 is a deficient number, since it is larger than the sum of its proper divisors (16817354).

21021670 is a wasteful number, since it uses less digits than its factorization.

21021670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2102174.

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 21021670 is about 4584.9394761545. The cubic root of 21021670 is about 275.9872832480.

Adding to 21021670 its reverse (7612012), we get a palindrome (28633682).

The spelling of 21021670 in words is "twenty-one million, twenty-one thousand, six hundred seventy".