21021020213 has 8 divisors (see below), whose sum is σ = 21519966936. Its totient is φ = 20527776000.

The previous prime is 21021020161. The next prime is 21021020239. The reversal of 21021020213 is 31202012012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 13474102084 + 7546918129 = 116078^2 + 86873^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21021020213 - 2¹⁶ = 21020954677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021020513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1418168 + ... + 1432913.

It is an arithmetic number, because the mean of its divisors is an integer number (2689995867).

Almost surely, 2^21021020213 is an apocalyptic number.

It is an amenable number.

21021020213 is a deficient number, since it is larger than the sum of its proper divisors (498946723).

21021020213 is a wasteful number, since it uses less digits than its factorization.

21021020213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2851255.

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21021020213 its reverse (31202012012), we get a palindrome (52223032225).

The spelling of 21021020213 in words is "twenty-one billion, twenty-one million, twenty thousand, two hundred thirteen".