81731061625 has 8 divisors (see below), whose sum is σ = 102000365064. Its totient is φ = 65384849200.

The previous prime is 81731061593. The next prime is 81731061631. The reversal of 81731061625 is 52616013718.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 20785277241 + 60945784384 = 144171^2 + 246872^2 .

It is not a de Polignac number, because 81731061625 - 2⁵ = 81731061593 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 326924122 + ... + 326924371.

It is an arithmetic number, because the mean of its divisors is an integer number (12750045633).

Almost surely, 2^81731061625 is an apocalyptic number.

It is an amenable number.

81731061625 is a deficient number, since it is larger than the sum of its proper divisors (20269303439).

81731061625 is an equidigital number, since it uses as much as digits as its factorization.

81731061625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 653848508 (or 653848498 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 40.

The spelling of 81731061625 in words is "eighty-one billion, seven hundred thirty-one million, sixty-one thousand, six hundred twenty-five".