6509981557 has 2 divisors, whose sum is σ = 6509981558. Its totient is φ = 6509981556.

The previous prime is 6509981497. The next prime is 6509981561. The reversal of 6509981557 is 7551899056.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3629942001 + 2880039556 = 60249^2 + 53666^2 .

It is a cyclic number.

It is not a de Polignac number, because 6509981557 - 2²³ = 6501592949 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6509981498 and 6509981507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6509981657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3254990778 + 3254990779.

It is an arithmetic number, because the mean of its divisors is an integer number (3254990779).

Almost surely, 2^6509981557 is an apocalyptic number.

It is an amenable number.

6509981557 is a deficient number, since it is larger than the sum of its proper divisors (1).

6509981557 is an equidigital number, since it uses as much as digits as its factorization.

6509981557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3402000, while the sum is 55.

The square root of 6509981557 is about 80684.4567249480. The cubic root of 6509981557 is about 1867.2103788849.

The spelling of 6509981557 in words is "six billion, five hundred nine million, nine hundred eighty-one thousand, five hundred fifty-seven".