81481520 has 40 divisors (see below), whose sum is σ = 189821184. Its totient is φ = 32527872.

The previous prime is 81481513. The next prime is 81481529. The reversal of 81481520 is 2518418.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (81481529) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74417 + ... + 75503.

Almost surely, 2^81481520 is an apocalyptic number.

81481520 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81481520 is an abundant number, since it is smaller than the sum of its proper divisors (108339664).

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

81481520 is a wasteful number, since it uses less digits than its factorization.

81481520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2037 (or 2031 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 29.

The square root of 81481520 is about 9026.7114720700. The cubic root of 81481520 is about 433.5305505977.

Adding to 81481520 its reverse (2518418), we get a palindrome (83999938).

The spelling of 81481520 in words is "eighty-one million, four hundred eighty-one thousand, five hundred twenty".