81507216 has 160 divisors (see below), whose sum is σ = 257126400. Its totient is φ = 21745152.

The previous prime is 81507211. The next prime is 81507227. The reversal of 81507216 is 61270518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81507211) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 409485 + ... + 409683.

It is an arithmetic number, because the mean of its divisors is an integer number (1607040).

Almost surely, 2^81507216 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 81507216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128563200).

81507216 is an abundant number, since it is smaller than the sum of its proper divisors (175619184).

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

81507216 is a wasteful number, since it uses less digits than its factorization.

81507216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 293 (or 287 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 30.

The square root of 81507216 is about 9028.1346910644. The cubic root of 81507216 is about 433.5761185179.

The spelling of 81507216 in words is "eighty-one million, five hundred seven thousand, two hundred sixteen".