81305985025 has 12 divisors (see below), whose sum is σ = 102964516992. Its totient is φ = 63660855440.

The previous prime is 81305984993. The next prime is 81305985029. The reversal of 81305985025 is 52058950318.

It is not a de Polignac number, because 81305985025 - 2⁵ = 81305984993 is a prime.

It is a super-2 number, since 2×81305985025² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81305985029) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 34597117 + ... + 34599466.

It is an arithmetic number, because the mean of its divisors is an integer number (8580376416).

Almost surely, 2^81305985025 is an apocalyptic number.

It is an amenable number.

81305985025 is a deficient number, since it is larger than the sum of its proper divisors (21658531967).

81305985025 is a wasteful number, since it uses less digits than its factorization.

81305985025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69196640 (or 69196635 counting only the distinct ones).

The product of its (nonzero) digits is 432000, while the sum is 46.

The spelling of 81305985025 in words is "eighty-one billion, three hundred five million, nine hundred eighty-five thousand, twenty-five".