8161661 has 2 divisors, whose sum is σ = 8161662. Its totient is φ = 8161660.

The previous prime is 8161631. The next prime is 8161667. The reversal of 8161661 is 1661618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4280761 + 3880900 = 2069^2 + 1970^2 .

It is a cyclic number.

It is not a de Polignac number, because 8161661 - 2¹⁰ = 8160637 is a prime.

It is a super-2 number, since 2×8161661² = 133225420557842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8161667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4080830 + 4080831.

It is an arithmetic number, because the mean of its divisors is an integer number (4080831).

Almost surely, 2^8161661 is an apocalyptic number.

It is an amenable number.

8161661 is a deficient number, since it is larger than the sum of its proper divisors (1).

8161661 is an equidigital number, since it uses as much as digits as its factorization.

8161661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 29.

The square root of 8161661 is about 2856.8620897761. The cubic root of 8161661 is about 201.3382011186.

The spelling of 8161661 in words is "eight million, one hundred sixty-one thousand, six hundred sixty-one".