6557800661 has 2 divisors, whose sum is σ = 6557800662. Its totient is φ = 6557800660.

The previous prime is 6557800651. The next prime is 6557800693. The reversal of 6557800661 is 1660087556.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6125410225 + 432390436 = 78265^2 + 20794^2 .

It is a cyclic number.

It is not a de Polignac number, because 6557800661 - 2¹⁸ = 6557538517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6557800621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3278900330 + 3278900331.

It is an arithmetic number, because the mean of its divisors is an integer number (3278900331).

Almost surely, 2^6557800661 is an apocalyptic number.

It is an amenable number.

6557800661 is a deficient number, since it is larger than the sum of its proper divisors (1).

6557800661 is an equidigital number, since it uses as much as digits as its factorization.

6557800661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 302400, while the sum is 44.

The square root of 6557800661 is about 80980.2485856891. The cubic root of 6557800661 is about 1871.7710980261.

The spelling of 6557800661 in words is "six billion, five hundred fifty-seven million, eight hundred thousand, six hundred sixty-one".