213021021 has 16 divisors (see below), whose sum is σ = 287630784. Its totient is φ = 140219904.

The previous prime is 213021013. The next prime is 213021041. The reversal of 213021021 is 120120312.

It is not a de Polignac number, because 213021021 - 2³ = 213021013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 213020988 and 213021006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213021001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 224470 + ... + 225416.

It is an arithmetic number, because the mean of its divisors is an integer number (17976924).

Almost surely, 2^213021021 is an apocalyptic number.

It is an amenable number.

213021021 is a deficient number, since it is larger than the sum of its proper divisors (74609763).

213021021 is an equidigital number, since it uses as much as digits as its factorization.

213021021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1820.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 213021021 is about 14595.2396691524. The cubic root of 213021021 is about 597.2289075584.

Adding to 213021021 its reverse (120120312), we get a palindrome (333141333).

The spelling of 213021021 in words is "two hundred thirteen million, twenty-one thousand, twenty-one".