21075670 has 64 divisors (see below), whose sum is σ = 47941632. Its totient is φ = 6480000.

The previous prime is 21075661. The next prime is 21075671. The reversal of 21075670 is 7657012.

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21075671) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 77635 + ... + 77905.

It is an arithmetic number, because the mean of its divisors is an integer number (749088).

Almost surely, 2^21075670 is an apocalyptic number.

21075670 is an abundant number, since it is smaller than the sum of its proper divisors (26865962).

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

21075670 is a wasteful number, since it uses less digits than its factorization.

21075670 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397.

The product of its (nonzero) digits is 2940, while the sum is 28.

The square root of 21075670 is about 4590.8245446760. The cubic root of 21075670 is about 276.2233978601.

It can be divided in two parts, 2107 and 5670, that added together give a palindrome (7777).

The spelling of 21075670 in words is "twenty-one million, seventy-five thousand, six hundred seventy".