81914980561 has 2 divisors, whose sum is σ = 81914980562. Its totient is φ = 81914980560.

The previous prime is 81914980489. The next prime is 81914980597. The reversal of 81914980561 is 16508941918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79316020161 + 2598960400 = 281631^2 + 50980^2 .

It is a cyclic number.

It is not a de Polignac number, because 81914980561 - 2¹³ = 81914972369 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81914980499 and 81914980508.

It is not a weakly prime, because it can be changed into another prime (81914983561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40957490280 + 40957490281.

It is an arithmetic number, because the mean of its divisors is an integer number (40957490281).

Almost surely, 2^81914980561 is an apocalyptic number.

It is an amenable number.

81914980561 is a deficient number, since it is larger than the sum of its proper divisors (1).

81914980561 is an equidigital number, since it uses as much as digits as its factorization.

81914980561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 622080, while the sum is 52.

The spelling of 81914980561 in words is "eighty-one billion, nine hundred fourteen million, nine hundred eighty thousand, five hundred sixty-one".