81306738 has 48 divisors (see below), whose sum is σ = 191443200. Its totient is φ = 24844320.

The previous prime is 81306737. The next prime is 81306781. The reversal of 81306738 is 83760318.

It is a super-2 number, since 2×81306738² = 13221571288401288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81306737) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6768 + ... + 14436.

It is an arithmetic number, because the mean of its divisors is an integer number (3988400).

Almost surely, 2^81306738 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81306738, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (95721600).

81306738 is an abundant number, since it is smaller than the sum of its proper divisors (110136462).

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

81306738 is a wasteful number, since it uses less digits than its factorization.

81306738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7727 (or 7724 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 81306738 is about 9017.0248973816. The cubic root of 81306738 is about 433.2203470056.

The spelling of 81306738 in words is "eighty-one million, three hundred six thousand, seven hundred thirty-eight".