81949982977 has 2 divisors, whose sum is σ = 81949982978. Its totient is φ = 81949982976.

The previous prime is 81949982909. The next prime is 81949983079. The reversal of 81949982977 is 77928994918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65037240576 + 16912742401 = 255024^2 + 130049^2 .

It is a cyclic number.

It is not a de Polignac number, because 81949982977 - 2²⁷ = 81815765249 is a prime.

It is not a weakly prime, because it can be changed into another prime (81949985977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40974991488 + 40974991489.

It is an arithmetic number, because the mean of its divisors is an integer number (40974991489).

Almost surely, 2^81949982977 is an apocalyptic number.

It is an amenable number.

81949982977 is a deficient number, since it is larger than the sum of its proper divisors (1).

81949982977 is an equidigital number, since it uses as much as digits as its factorization.

81949982977 is an evil number, because the sum of its binary digits is even.

The product of its digits is 164602368, while the sum is 73.

The spelling of 81949982977 in words is "eighty-one billion, nine hundred forty-nine million, nine hundred eighty-two thousand, nine hundred seventy-seven".