21021001213 has 2 divisors, whose sum is σ = 21021001214. Its totient is φ = 21021001212.

The previous prime is 21021001193. The next prime is 21021001231. The reversal of 21021001213 is 31210012012.

Together with next prime (21021001231) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16087624569 + 4933376644 = 126837^2 + 70238^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021001213 - 2⁵ = 21021001181 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21021001193 and 21021001202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021001283) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510500606 + 10510500607.

It is an arithmetic number, because the mean of its divisors is an integer number (10510500607).

Almost surely, 2^21021001213 is an apocalyptic number.

It is an amenable number.

21021001213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021001213 is an equidigital number, since it uses as much as digits as its factorization.

21021001213 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21021001213 its reverse (31210012012), we get a palindrome (52231013225).

The spelling of 21021001213 in words is "twenty-one billion, twenty-one million, one thousand, two hundred thirteen".