6656401 has 4 divisors (see below), whose sum is σ = 7047972. Its totient is φ = 6264832.

The previous prime is 6656393. The next prime is 6656437. The reversal of 6656401 is 1046566.

It is a Cunningham number, because it is equal to 2580²+1.

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 5180176 + 1476225 = 2276^2 + 1215^2 .

It is a cyclic number.

It is not a de Polignac number, because 6656401 - 2³ = 6656393 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 6656401.

It is not an unprimeable number, because it can be changed into a prime (6656471) 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, 195760 + ... + 195793.

It is an arithmetic number, because the mean of its divisors is an integer number (1761993).

Almost surely, 2^6656401 is an apocalyptic number.

It is an amenable number.

6656401 is a deficient number, since it is larger than the sum of its proper divisors (391571).

6656401 is a wasteful number, since it uses less digits than its factorization.

6656401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 391570.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 6656401 is about 2580.0001937984. Note that the first 3 decimals coincide. The cubic root of 6656401 is about 188.1105525268.

The spelling of 6656401 in words is "six million, six hundred fifty-six thousand, four hundred one".