6561641 has 4 divisors (see below), whose sum is σ = 6566784. Its totient is φ = 6556500.

The previous prime is 6561637. The next prime is 6561649. The reversal of 6561641 is 1461656.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 6561641 - 2² = 6561637 is a prime.

It is a super-2 number, since 2×6561641² = 86110265225762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6561649) 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, 956 + ... + 3746.

It is an arithmetic number, because the mean of its divisors is an integer number (1641696).

Almost surely, 2^6561641 is an apocalyptic number.

It is an amenable number.

6561641 is a deficient number, since it is larger than the sum of its proper divisors (5143).

6561641 is a wasteful number, since it uses less digits than its factorization.

6561641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5142.

The product of its digits is 4320, while the sum is 29.

The square root of 6561641 is about 2561.5700263705. The cubic root of 6561641 is about 187.2136405096.

The spelling of 6561641 in words is "six million, five hundred sixty-one thousand, six hundred forty-one".