81516240 has 160 divisors (see below), whose sum is σ = 302480640. Its totient is φ = 20058624.

The previous prime is 81516221. The next prime is 81516277. The reversal of 81516240 is 4261518.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26629 + ... + 29531.

It is an arithmetic number, because the mean of its divisors is an integer number (1890504).

Almost surely, 2^81516240 is an apocalyptic number.

81516240 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 81516240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (151240320).

81516240 is an abundant number, since it is smaller than the sum of its proper divisors (220964400).

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

81516240 is a wasteful number, since it uses less digits than its factorization.

81516240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2938 (or 2926 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 81516240 is about 9028.6344482430. The cubic root of 81516240 is about 433.5921189274.

Adding to 81516240 its reverse (4261518), we get a palindrome (85777758).

The spelling of 81516240 in words is "eighty-one million, five hundred sixteen thousand, two hundred forty".