7820656365521 has 4 divisors (see below), whose sum is σ = 7820662342500. Its totient is φ = 7820650388544.

The previous prime is 7820656365497. The next prime is 7820656365523. The reversal of 7820656365521 is 1255636560287.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1992106416400 + 5828549949121 = 1411420^2 + 2414239^2 .

It is a cyclic number.

It is not a de Polignac number, because 7820656365521 - 2¹⁰ = 7820656364497 is a prime.

It is a super-2 number, since 2×7820656365521² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7820656365523) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86396 + ... + 3955853.

It is an arithmetic number, because the mean of its divisors is an integer number (1955165585625).

Almost surely, 2^{7820656365521} is an apocalyptic number.

It is an amenable number.

7820656365521 is a deficient number, since it is larger than the sum of its proper divisors (5976979).

7820656365521 is a wasteful number, since it uses less digits than its factorization.

7820656365521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5976978.

The product of its (nonzero) digits is 18144000, while the sum is 56.

The spelling of 7820656365521 in words is "seven trillion, eight hundred twenty billion, six hundred fifty-six million, three hundred sixty-five thousand, five hundred twenty-one".