6640906061 has 4 divisors (see below), whose sum is σ = 7031547612. Its totient is φ = 6250264512.

The previous prime is 6640906057. The next prime is 6640906121. The reversal of 6640906061 is 1606090466.

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 4060875625 + 2580030436 = 63725^2 + 50794^2 .

It is a cyclic number.

It is not a de Polignac number, because 6640906061 - 2² = 6640906057 is a prime.

It is a super-2 number, since 2×6640906061² = 88203266622053071442, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6640906021) 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, 195320750 + ... + 195320783.

It is an arithmetic number, because the mean of its divisors is an integer number (1757886903).

Almost surely, 2^6640906061 is an apocalyptic number.

It is an amenable number.

6640906061 is a deficient number, since it is larger than the sum of its proper divisors (390641551).

6640906061 is a wasteful number, since it uses less digits than its factorization.

6640906061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390641550.

The product of its (nonzero) digits is 46656, while the sum is 38.

The square root of 6640906061 is about 81491.7545583601. The cubic root of 6640906061 is about 1879.6447628371.

The spelling of 6640906061 in words is "six billion, six hundred forty million, nine hundred six thousand, sixty-one".