21001023312121 has 2 divisors, whose sum is σ = 21001023312122. Its totient is φ = 21001023312120.

The previous prime is 21001023312079. The next prime is 21001023312127. The reversal of 21001023312121 is 12121332010012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15710632304896 + 5290391007225 = 3963664^2 + 2300085^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001023312121 - 2¹³ = 21001023303929 is a prime.

It is not a weakly prime, because it can be changed into another prime (21001023312127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500511656060 + 10500511656061.

It is an arithmetic number, because the mean of its divisors is an integer number (10500511656061).

Almost surely, 2^{21001023312121} is an apocalyptic number.

It is an amenable number.

21001023312121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001023312121 is an equidigital number, since it uses as much as digits as its factorization.

21001023312121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 19.

Adding to 21001023312121 its reverse (12121332010012), we get a palindrome (33122355322133).

The spelling of 21001023312121 in words is "twenty-one trillion, one billion, twenty-three million, three hundred twelve thousand, one hundred twenty-one".