81337520 has 80 divisors (see below), whose sum is σ = 218477088. Its totient is φ = 27832320.

The previous prime is 81337519. The next prime is 81337523. The reversal of 81337520 is 2573318.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (81337523) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12242 + ... + 17678.

Almost surely, 2^81337520 is an apocalyptic number.

81337520 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81337520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109238544).

81337520 is an abundant number, since it is smaller than the sum of its proper divisors (137139568).

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

81337520 is a wasteful number, since it uses less digits than its factorization.

81337520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5478 (or 5472 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 81337520 is about 9018.7316181379. The cubic root of 81337520 is about 433.2750112172.

The spelling of 81337520 in words is "eighty-one million, three hundred thirty-seven thousand, five hundred twenty".