81258520 has 32 divisors (see below), whose sum is σ = 208951200. Its totient is φ = 27859968.

The previous prime is 81258511. The next prime is 81258523. The reversal of 81258520 is 2585218.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81258523) 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 7 ways as a sum of consecutive naturals, for example, 144825 + ... + 145384.

It is an arithmetic number, because the mean of its divisors is an integer number (6529725).

Almost surely, 2^81258520 is an apocalyptic number.

It is an amenable number.

81258520 is an abundant number, since it is smaller than the sum of its proper divisors (127692680).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81258520 is a wasteful number, since it uses less digits than its factorization.

81258520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290227 (or 290223 counting only the distinct ones).

The product of its (nonzero) digits is 6400, while the sum is 31.

The square root of 81258520 is about 9014.3507808383. The cubic root of 81258520 is about 433.1346913355.

The spelling of 81258520 in words is "eighty-one million, two hundred fifty-eight thousand, five hundred twenty".