80725785661 has 2 divisors, whose sum is σ = 80725785662. Its totient is φ = 80725785660.

The previous prime is 80725785653. The next prime is 80725785671. The reversal of 80725785661 is 16658752708.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 75237198436 + 5488587225 = 274294^2 + 74085^2 .

It is a cyclic number.

It is not a de Polignac number, because 80725785661 - 2³ = 80725785653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (80725785671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40362892830 + 40362892831.

It is an arithmetic number, because the mean of its divisors is an integer number (40362892831).

Almost surely, 2^80725785661 is an apocalyptic number.

It is an amenable number.

80725785661 is a deficient number, since it is larger than the sum of its proper divisors (1).

80725785661 is an equidigital number, since it uses as much as digits as its factorization.

80725785661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5644800, while the sum is 55.

The spelling of 80725785661 in words is "eighty billion, seven hundred twenty-five million, seven hundred eighty-five thousand, six hundred sixty-one".