6561091 has 2 divisors, whose sum is σ = 6561092. Its totient is φ = 6561090.

The previous prime is 6561089. The next prime is 6561097. The reversal of 6561091 is 1901656.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6561091 - 2¹ = 6561089 is a prime.

It is a super-2 number, since 2×6561091² = 86095830220562, which contains 22 as substring.

Together with 6561089, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (6561097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3280545 + 3280546.

It is an arithmetic number, because the mean of its divisors is an integer number (3280546).

Almost surely, 2^6561091 is an apocalyptic number.

6561091 is a deficient number, since it is larger than the sum of its proper divisors (1).

6561091 is an equidigital number, since it uses as much as digits as its factorization.

6561091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1620, while the sum is 28.

The square root of 6561091 is about 2561.4626680863. The cubic root of 6561091 is about 187.2084095834.

The spelling of 6561091 in words is "six million, five hundred sixty-one thousand, ninety-one".