6640501961 has 2 divisors, whose sum is σ = 6640501962. Its totient is φ = 6640501960.

The previous prime is 6640501943. The next prime is 6640501993. The reversal of 6640501961 is 1691050466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6292455625 + 348046336 = 79325^2 + 18656^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6640501961 is a prime.

It is not a weakly prime, because it can be changed into another prime (6640501921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3320250980 + 3320250981.

It is an arithmetic number, because the mean of its divisors is an integer number (3320250981).

Almost surely, 2^6640501961 is an apocalyptic number.

It is an amenable number.

6640501961 is a deficient number, since it is larger than the sum of its proper divisors (1).

6640501961 is an equidigital number, since it uses as much as digits as its factorization.

6640501961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 6640501961 is about 81489.2751286941. The cubic root of 6640501961 is about 1879.6066365207.

The spelling of 6640501961 in words is "six billion, six hundred forty million, five hundred one thousand, nine hundred sixty-one".