1865001661 has 2 divisors, whose sum is σ = 1865001662. Its totient is φ = 1865001660.

The previous prime is 1865001599. The next prime is 1865001673. The reversal of 1865001661 is 1661005681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1763496036 + 101505625 = 41994^2 + 10075^2 .

It is a cyclic number.

It is not a de Polignac number, because 1865001661 - 2¹⁵ = 1864968893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1865005661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 932500830 + 932500831.

It is an arithmetic number, because the mean of its divisors is an integer number (932500831).

Almost surely, 2^1865001661 is an apocalyptic number.

It is an amenable number.

1865001661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1865001661 is an equidigital number, since it uses as much as digits as its factorization.

1865001661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 1865001661 is about 43185.6649943011. The cubic root of 1865001661 is about 1230.9103052650.

The spelling of 1865001661 in words is "one billion, eight hundred sixty-five million, one thousand, six hundred sixty-one".