6640961 has 4 divisors (see below), whose sum is σ = 6657924. Its totient is φ = 6624000.

The previous prime is 6640939. The next prime is 6640967. The reversal of 6640961 is 1690466.

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 3682561 + 2958400 = 1919^2 + 1720^2 .

It is a cyclic number.

It is not a de Polignac number, because 6640961 - 2¹⁰ = 6639937 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (6640967) 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, 7880 + ... + 8681.

It is an arithmetic number, because the mean of its divisors is an integer number (1664481).

Almost surely, 2^6640961 is an apocalyptic number.

It is an amenable number.

6640961 is a deficient number, since it is larger than the sum of its proper divisors (16963).

6640961 is a wasteful number, since it uses less digits than its factorization.

6640961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16962.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 6640961 is about 2577.0062087624. The cubic root of 6640961 is about 187.9649946142.

Subtracting from 6640961 its sum of digits (32), we obtain a square (6640929 = 2577²).

The spelling of 6640961 in words is "six million, six hundred forty thousand, nine hundred sixty-one".