81907518 has 192 divisors, whose sum is σ = 231137280. Its totient is φ = 19051200.

The previous prime is 81907493. The next prime is 81907519. The reversal of 81907518 is 81570918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81907519) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1904805 + ... + 1904847.

It is an arithmetic number, because the mean of its divisors is an integer number (1203840).

Almost surely, 2^81907518 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81907518, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (115568640).

81907518 is an abundant number, since it is smaller than the sum of its proper divisors (149229762).

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

81907518 is a wasteful number, since it uses less digits than its factorization.

81907518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123 (or 116 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 39.

The square root of 81907518 is about 9050.2772333227. The cubic root of 81907518 is about 434.2847593572.

The spelling of 81907518 in words is "eighty-one million, nine hundred seven thousand, five hundred eighteen".