21011101210621 has 2 divisors, whose sum is σ = 21011101210622. Its totient is φ = 21011101210620.

The previous prime is 21011101210549. The next prime is 21011101210633. The reversal of 21011101210621 is 12601210111012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19287292392900 + 1723808817721 = 4391730^2 + 1312939^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011101210621 - 2²¹ = 21011099113469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21011101210651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505550605310 + 10505550605311.

It is an arithmetic number, because the mean of its divisors is an integer number (10505550605311).

Almost surely, 2^{21011101210621} is an apocalyptic number.

It is an amenable number.

21011101210621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011101210621 is an equidigital number, since it uses as much as digits as its factorization.

21011101210621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 19.

Adding to 21011101210621 its reverse (12601210111012), we get a palindrome (33612311321633).

The spelling of 21011101210621 in words is "twenty-one trillion, eleven billion, one hundred one million, two hundred ten thousand, six hundred twenty-one".