81520416 has 72 divisors (see below), whose sum is σ = 234823680. Its totient is φ = 26822016.

The previous prime is 81520403. The next prime is 81520427. The reversal of 81520416 is 61402518.

It is a tau number, because it is divible by the number of its divisors (72).

It is a self number, because there is not a number n which added to its sum of digits gives 81520416.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20961 + ... + 24543.

It is an arithmetic number, because the mean of its divisors is an integer number (3261440).

Almost surely, 2^81520416 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81520416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117411840).

81520416 is an abundant number, since it is smaller than the sum of its proper divisors (153303264).

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

81520416 is a wasteful number, since it uses less digits than its factorization.

81520416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3678 (or 3667 counting only the distinct ones).

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

The square root of 81520416 is about 9028.8657094898. The cubic root of 81520416 is about 433.5995229726.

The spelling of 81520416 in words is "eighty-one million, five hundred twenty thousand, four hundred sixteen".