81503616 has 64 divisors (see below), whose sum is σ = 227908800. Its totient is φ = 25735680.

The previous prime is 81503581. The next prime is 81503621. The reversal of 81503616 is 61630518.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1711 + ... + 12881.

It is an arithmetic number, because the mean of its divisors is an integer number (3561075).

Almost surely, 2^81503616 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 81503616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113954400).

81503616 is an abundant number, since it is smaller than the sum of its proper divisors (146405184).

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

81503616 is a wasteful number, since it uses less digits than its factorization.

81503616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11207 (or 11195 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 30.

The square root of 81503616 is about 9027.9353121298. The cubic root of 81503616 is about 433.5697350462.

The spelling of 81503616 in words is "eighty-one million, five hundred three thousand, six hundred sixteen".