21002170 has 32 divisors (see below), whose sum is σ = 43452288. Its totient is φ = 7159488.

The previous prime is 21002129. The next prime is 21002203. The reversal of 21002170 is 7120012.

It is a super-2 number, since 2×21002170² = 882182289417800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21002170.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13029 + ... + 14551.

It is an arithmetic number, because the mean of its divisors is an integer number (1357884).

Almost surely, 2^21002170 is an apocalyptic number.

21002170 is an abundant number, since it is smaller than the sum of its proper divisors (22450118).

21002170 is a wasteful number, since it uses less digits than its factorization.

21002170 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1734.

The product of its (nonzero) digits is 28, while the sum is 13.

The square root of 21002170 is about 4582.8124552506. The cubic root of 21002170 is about 275.9019202719.

Adding to 21002170 its reverse (7120012), we get a palindrome (28122182).

The spelling of 21002170 in words is "twenty-one million, two thousand, one hundred seventy".