21071670 has 64 divisors (see below), whose sum is σ = 54328320. Its totient is φ = 5211648.

The previous prime is 21071647. The next prime is 21071683. The reversal of 21071670 is 7617012.

It is a self number, because there is not a number n which added to its sum of digits gives 21071670.

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 31 ways as a sum of consecutive naturals, for example, 40029 + ... + 40551.

It is an arithmetic number, because the mean of its divisors is an integer number (848880).

Almost surely, 2^21071670 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21071670, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27164160).

21071670 is an abundant number, since it is smaller than the sum of its proper divisors (33256650).

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

21071670 is a wasteful number, since it uses less digits than its factorization.

21071670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 629.

The product of its (nonzero) digits is 588, while the sum is 24.

The square root of 21071670 is about 4590.3888724159. The cubic root of 21071670 is about 276.2059217293.

Adding to 21071670 its reverse (7617012), we get a palindrome (28688682).

The spelling of 21071670 in words is "twenty-one million, seventy-one thousand, six hundred seventy".