81808619741 has 2 divisors, whose sum is σ = 81808619742. Its totient is φ = 81808619740.

The previous prime is 81808619681. The next prime is 81808619759. The reversal of 81808619741 is 14791680818.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 50065852516 + 31742767225 = 223754^2 + 178165^2 .

It is a cyclic number.

It is not a de Polignac number, because 81808619741 - 2³⁰ = 80734877917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81808619141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40904309870 + 40904309871.

It is an arithmetic number, because the mean of its divisors is an integer number (40904309871).

Almost surely, 2^81808619741 is an apocalyptic number.

It is an amenable number.

81808619741 is a deficient number, since it is larger than the sum of its proper divisors (1).

81808619741 is an equidigital number, since it uses as much as digits as its factorization.

81808619741 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 774144, while the sum is 53.

The spelling of 81808619741 in words is "eighty-one billion, eight hundred eight million, six hundred nineteen thousand, seven hundred forty-one".