6561961 has 8 divisors (see below), whose sum is σ = 7542720. Its totient is φ = 5592048.

The previous prime is 6561943. The next prime is 6561991. The reversal of 6561961 is 1691656.

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

It is not a de Polignac number, because 6561961 - 2⁷ = 6561833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6561911) 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, 1366 + ... + 3871.

It is an arithmetic number, because the mean of its divisors is an integer number (942840).

Almost surely, 2^6561961 is an apocalyptic number.

It is an amenable number.

6561961 is a deficient number, since it is larger than the sum of its proper divisors (980759).

6561961 is a wasteful number, since it uses less digits than its factorization.

6561961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5423.

The product of its digits is 9720, while the sum is 34.

The square root of 6561961 is about 2561.6324873018. The cubic root of 6561961 is about 187.2166838230.

It can be divided in two parts, 6561 and 961, that multiplied together give a square (6305121 = 2511²).

The spelling of 6561961 in words is "six million, five hundred sixty-one thousand, nine hundred sixty-one".