71661489649 has 2 divisors, whose sum is σ = 71661489650. Its totient is φ = 71661489648.

The previous prime is 71661489623. The next prime is 71661489721. The reversal of 71661489649 is 94698416617.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50988801249 + 20672688400 = 225807^2 + 143780^2 .

It is a cyclic number.

It is not a de Polignac number, because 71661489649 - 2¹⁹ = 71660965361 is a prime.

It is not a weakly prime, because it can be changed into another prime (71661489619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35830744824 + 35830744825.

It is an arithmetic number, because the mean of its divisors is an integer number (35830744825).

Almost surely, 2^71661489649 is an apocalyptic number.

It is an amenable number.

71661489649 is a deficient number, since it is larger than the sum of its proper divisors (1).

71661489649 is an equidigital number, since it uses as much as digits as its factorization.

71661489649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15676416, while the sum is 61.

The spelling of 71661489649 in words is "seventy-one billion, six hundred sixty-one million, four hundred eighty-nine thousand, six hundred forty-nine".