861664841 has 2 divisors, whose sum is σ = 861664842. Its totient is φ = 861664840.

The previous prime is 861664829. The next prime is 861664861. The reversal of 861664841 is 148466168.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 852873616 + 8791225 = 29204^2 + 2965^2 .

It is a cyclic number.

It is not a de Polignac number, because 861664841 - 2⁶ = 861664777 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 861664792 and 861664801.

It is not a weakly prime, because it can be changed into another prime (861664861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430832420 + 430832421.

It is an arithmetic number, because the mean of its divisors is an integer number (430832421).

Almost surely, 2^861664841 is an apocalyptic number.

It is an amenable number.

861664841 is a deficient number, since it is larger than the sum of its proper divisors (1).

861664841 is an equidigital number, since it uses as much as digits as its factorization.

861664841 is an evil number, because the sum of its binary digits is even.

The product of its digits is 221184, while the sum is 44.

The square root of 861664841 is about 29354.1281764593. The cubic root of 861664841 is about 951.5817935882.

The spelling of 861664841 in words is "eight hundred sixty-one million, six hundred sixty-four thousand, eight hundred forty-one".