6561869 has 4 divisors (see below), whose sum is σ = 6626940. Its totient is φ = 6496800.

The previous prime is 6561857. The next prime is 6561871. The reversal of 6561869 is 9681656.

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 3960100 + 2601769 = 1990^2 + 1613^2 .

It is a cyclic number.

It is not a de Polignac number, because 6561869 - 2⁸ = 6561613 is a prime.

It is a super-2 number, since 2×6561869² = 86116249546322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6561809) 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, 32384 + ... + 32585.

It is an arithmetic number, because the mean of its divisors is an integer number (1656735).

Almost surely, 2^6561869 is an apocalyptic number.

It is an amenable number.

6561869 is a deficient number, since it is larger than the sum of its proper divisors (65071).

6561869 is a wasteful number, since it uses less digits than its factorization.

6561869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65070.

The product of its digits is 77760, while the sum is 41.

The square root of 6561869 is about 2561.6145299401. The cubic root of 6561869 is about 187.2158088805.

The spelling of 6561869 in words is "six million, five hundred sixty-one thousand, eight hundred sixty-nine".