8161538657 has 2 divisors, whose sum is σ = 8161538658. Its totient is φ = 8161538656.

The previous prime is 8161538647. The next prime is 8161538681. The reversal of 8161538657 is 7568351618.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7237925776 + 923612881 = 85076^2 + 30391^2 .

It is a cyclic number.

It is not a de Polignac number, because 8161538657 - 2²² = 8157344353 is a prime.

It is a super-2 number, since 2×8161538657² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (8161538647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4080769328 + 4080769329.

It is an arithmetic number, because the mean of its divisors is an integer number (4080769329).

Almost surely, 2^8161538657 is an apocalyptic number.

It is an amenable number.

8161538657 is a deficient number, since it is larger than the sum of its proper divisors (1).

8161538657 is an equidigital number, since it uses as much as digits as its factorization.

8161538657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1209600, while the sum is 50.

The square root of 8161538657 is about 90341.2345332960. The cubic root of 8161538657 is about 2013.3719509616.

The spelling of 8161538657 in words is "eight billion, one hundred sixty-one million, five hundred thirty-eight thousand, six hundred fifty-seven".