81601872 has 80 divisors (see below), whose sum is σ = 236240832. Its totient is φ = 24053760.

The previous prime is 81601867. The next prime is 81601873. The reversal of 81601872 is 27810618.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81601873) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17448 + ... + 21624.

Almost surely, 2^81601872 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 81601872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118120416).

81601872 is an abundant number, since it is smaller than the sum of its proper divisors (154638960).

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

81601872 is a wasteful number, since it uses less digits than its factorization.

81601872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4236 (or 4230 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 33.

The square root of 81601872 is about 9033.3754488563. The cubic root of 81601872 is about 433.7438938644.

The spelling of 81601872 in words is "eighty-one million, six hundred one thousand, eight hundred seventy-two".