6561935995261 has 4 divisors (see below), whose sum is σ = 6788209650300. Its totient is φ = 6335662340224.

The previous prime is 6561935995259. The next prime is 6561935995301. The reversal of 6561935995261 is 1625995391656.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1646820391225 + 4915115604036 = 1283285^2 + 2217006^2 .

It is a cyclic number.

It is not a de Polignac number, because 6561935995261 - 2¹ = 6561935995259 is a prime.

It is a super-2 number, since 2×6561935995261² (a number of 26 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6561935995211) 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, 113136827476 + ... + 113136827533.

It is an arithmetic number, because the mean of its divisors is an integer number (1697052412575).

Almost surely, 2^{6561935995261} is an apocalyptic number.

It is an amenable number.

6561935995261 is a deficient number, since it is larger than the sum of its proper divisors (226273655039).

6561935995261 is a wasteful number, since it uses less digits than its factorization.

6561935995261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226273655038.

The product of its digits is 118098000, while the sum is 67.

The spelling of 6561935995261 in words is "six trillion, five hundred sixty-one billion, nine hundred thirty-five million, nine hundred ninety-five thousand, two hundred sixty-one".