6616560001021 has 2 divisors, whose sum is σ = 6616560001022. Its totient is φ = 6616560001020.

The previous prime is 6616560001019. The next prime is 6616560001031. The reversal of 6616560001021 is 1201000656166.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3964837616100 + 2651722384921 = 1991190^2 + 1628411^2 .

It is a cyclic number.

It is not a de Polignac number, because 6616560001021 - 2¹ = 6616560001019 is a prime.

It is a super-2 number, since 2×6616560001021² (a number of 26 digits) contains 22 as substring.

Together with 6616560001019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6616560001031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3308280000510 + 3308280000511.

It is an arithmetic number, because the mean of its divisors is an integer number (3308280000511).

Almost surely, 2^{6616560001021} is an apocalyptic number.

It is an amenable number.

6616560001021 is a deficient number, since it is larger than the sum of its proper divisors (1).

6616560001021 is an equidigital number, since it uses as much as digits as its factorization.

6616560001021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12960, while the sum is 34.

Adding to 6616560001021 its reverse (1201000656166), we get a palindrome (7817560657187).

The spelling of 6616560001021 in words is "six trillion, six hundred sixteen billion, five hundred sixty million, one thousand, twenty-one".