81580425 has 24 divisors (see below), whose sum is σ = 140746944. Its totient is φ = 41616960.

The previous prime is 81580423. The next prime is 81580439. The reversal of 81580425 is 52408518.

It is not a de Polignac number, because 81580425 - 2¹ = 81580423 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81580423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21922 + ... + 25371.

It is an arithmetic number, because the mean of its divisors is an integer number (5864456).

Almost surely, 2^81580425 is an apocalyptic number.

It is an amenable number.

81580425 is a deficient number, since it is larger than the sum of its proper divisors (59166519).

81580425 is a wasteful number, since it uses less digits than its factorization.

81580425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47329 (or 47324 counting only the distinct ones).

The product of its (nonzero) digits is 12800, while the sum is 33.

The square root of 81580425 is about 9032.1882730599. The cubic root of 81580425 is about 433.7058909765.

The spelling of 81580425 in words is "eighty-one million, five hundred eighty thousand, four hundred twenty-five".