81385925 has 6 divisors (see below), whose sum is σ = 100918578. Its totient is φ = 65108720.

The previous prime is 81385921. The next prime is 81385933. The reversal of 81385925 is 52958318.

It can be written as a sum of positive squares in 3 ways, for example, as 3928324 + 77457601 = 1982^2 + 8801^2 .

It is not a de Polignac number, because 81385925 - 2² = 81385921 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81385921) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1627694 + ... + 1627743.

It is an arithmetic number, because the mean of its divisors is an integer number (16819763).

Almost surely, 2^81385925 is an apocalyptic number.

It is an amenable number.

81385925 is a deficient number, since it is larger than the sum of its proper divisors (19532653).

81385925 is a wasteful number, since it uses less digits than its factorization.

81385925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3255447 (or 3255442 counting only the distinct ones).

The product of its digits is 86400, while the sum is 41.

The square root of 81385925 is about 9021.4148003514. The cubic root of 81385925 is about 433.3609433427.

The spelling of 81385925 in words is "eighty-one million, three hundred eighty-five thousand, nine hundred twenty-five".