21021221002261 has 2 divisors, whose sum is σ = 21021221002262. Its totient is φ = 21021221002260.

The previous prime is 21021221002247. The next prime is 21021221002267. The reversal of 21021221002261 is 16220012212012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13587473282161 + 7433747720100 = 3686119^2 + 2726490^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021221002261 - 2¹³ = 21021220994069 is a prime.

It is a super-2 number, since 2×21021221002261² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021221002267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510610501130 + 10510610501131.

It is an arithmetic number, because the mean of its divisors is an integer number (10510610501131).

Almost surely, 2^{21021221002261} is an apocalyptic number.

It is an amenable number.

21021221002261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021221002261 is an equidigital number, since it uses as much as digits as its factorization.

21021221002261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 384, while the sum is 22.

Adding to 21021221002261 its reverse (16220012212012), we get a palindrome (37241233214273).

The spelling of 21021221002261 in words is "twenty-one trillion, twenty-one billion, two hundred twenty-one million, two thousand, two hundred sixty-one".