81211424 has 72 divisors (see below), whose sum is σ = 187766208. Its totient is φ = 34574400.

The previous prime is 81211421. The next prime is 81211439. The reversal of 81211424 is 42411218.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 81211424.

It is not an unprimeable number, because it can be changed into a prime (81211421) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 537749 + ... + 537899.

It is an arithmetic number, because the mean of its divisors is an integer number (2607864).

Almost surely, 2^81211424 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 81211424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (93883104).

81211424 is an abundant number, since it is smaller than the sum of its proper divisors (106554784).

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

81211424 is an frugal number, since it uses more digits than its factorization.

81211424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196 (or 160 counting only the distinct ones).

The product of its digits is 512, while the sum is 23.

The square root of 81211424 is about 9011.7381231370. The cubic root of 81211424 is about 433.0509960970.

The spelling of 81211424 in words is "eighty-one million, two hundred eleven thousand, four hundred twenty-four".