81632725861 has 2 divisors, whose sum is σ = 81632725862. Its totient is φ = 81632725860.

The previous prime is 81632725789. The next prime is 81632725891. The reversal of 81632725861 is 16852723618.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70652829636 + 10979896225 = 265806^2 + 104785^2 .

It is a cyclic number.

It is not a de Polignac number, because 81632725861 - 2¹³ = 81632717669 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81632725891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40816362930 + 40816362931.

It is an arithmetic number, because the mean of its divisors is an integer number (40816362931).

Almost surely, 2^81632725861 is an apocalyptic number.

It is an amenable number.

81632725861 is a deficient number, since it is larger than the sum of its proper divisors (1).

81632725861 is an equidigital number, since it uses as much as digits as its factorization.

81632725861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 967680, while the sum is 49.

The spelling of 81632725861 in words is "eighty-one billion, six hundred thirty-two million, seven hundred twenty-five thousand, eight hundred sixty-one".