6561864893 has 4 divisors (see below), whose sum is σ = 6562473120. Its totient is φ = 6561256668.

The previous prime is 6561864853. The next prime is 6561864929. The reversal of 6561864893 is 3984681656.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6561864893 - 2³² = 2266897597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6561864853) 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, 287633 + ... + 309606.

It is an arithmetic number, because the mean of its divisors is an integer number (1640618280).

Almost surely, 2^6561864893 is an apocalyptic number.

It is an amenable number.

6561864893 is a deficient number, since it is larger than the sum of its proper divisors (608227).

6561864893 is a wasteful number, since it uses less digits than its factorization.

6561864893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 608226.

The product of its digits is 7464960, while the sum is 56.

The square root of 6561864893 is about 81005.3386697445. The cubic root of 6561864893 is about 1872.1576982177.

The spelling of 6561864893 in words is "six billion, five hundred sixty-one million, eight hundred sixty-four thousand, eight hundred ninety-three".