6561722369 has 8 divisors (see below), whose sum is σ = 6736753800. Its totient is φ = 6387404800.

The previous prime is 6561722329. The next prime is 6561722389. The reversal of 6561722369 is 9632271656.

It can be written as a sum of positive squares in 4 ways, for example, as 1512198769 + 5049523600 = 38887^2 + 71060^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6561722369 - 2⁸ = 6561722113 is a prime.

It is a super-2 number, since 2×6561722369² = 86112400895669944322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6561722309) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 159812 + ... + 196629.

It is an arithmetic number, because the mean of its divisors is an integer number (842094225).

Almost surely, 2^6561722369 is an apocalyptic number.

It is an amenable number.

6561722369 is a deficient number, since it is larger than the sum of its proper divisors (175031431).

6561722369 is a wasteful number, since it uses less digits than its factorization.

6561722369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356931.

The product of its digits is 816480, while the sum is 47.

The square root of 6561722369 is about 81004.4589451717. The cubic root of 6561722369 is about 1872.1441436699.

The spelling of 6561722369 in words is "six billion, five hundred sixty-one million, seven hundred twenty-two thousand, three hundred sixty-nine".