81505425 has 48 divisors (see below), whose sum is σ = 139673600. Its totient is φ = 41912640.

The previous prime is 81505397. The next prime is 81505427. The reversal of 81505425 is 52450518.

It is not a de Polignac number, because 81505425 - 2⁵ = 81505393 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81505392 and 81505401.

It is not an unprimeable number, because it can be changed into a prime (81505427) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 409476 + ... + 409674.

Almost surely, 2^81505425 is an apocalyptic number.

It is an amenable number.

81505425 is a deficient number, since it is larger than the sum of its proper divisors (58168175).

81505425 is a wasteful number, since it uses less digits than its factorization.

81505425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 382 (or 377 counting only the distinct ones).

The product of its (nonzero) digits is 8000, while the sum is 30.

The square root of 81505425 is about 9028.0355005948. The cubic root of 81505425 is about 433.5729427642.

The spelling of 81505425 in words is "eighty-one million, five hundred five thousand, four hundred twenty-five".