81697872 has 80 divisors (see below), whose sum is σ = 229896000. Its totient is φ = 24901632.

The previous prime is 81697867. The next prime is 81697873. The reversal of 81697872 is 27879618.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81697873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24904 + ... + 27992.

It is an arithmetic number, because the mean of its divisors is an integer number (2873700).

Almost surely, 2^81697872 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 81697872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114948000).

81697872 is an abundant number, since it is smaller than the sum of its proper divisors (148198128).

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

81697872 is a wasteful number, since it uses less digits than its factorization.

81697872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3148 (or 3142 counting only the distinct ones).

The product of its digits is 338688, while the sum is 48.

The square root of 81697872 is about 9038.6875153420. The cubic root of 81697872 is about 433.9139189494.

The spelling of 81697872 in words is "eighty-one million, six hundred ninety-seven thousand, eight hundred seventy-two".