81436572 has 72 divisors (see below), whose sum is σ = 236107872. Its totient is φ = 23184000.

The previous prime is 81436559. The next prime is 81436573. The reversal of 81436572 is 27563418.

81436572 is a `hidden beast` number, since 81 + 4 + 3 + 6 + 572 = 666.

It is a super-3 number, since 3×81436572³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81436573) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 115822 + ... + 116522.

It is an arithmetic number, because the mean of its divisors is an integer number (3279276).

Almost surely, 2^81436572 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 81436572, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118053936).

81436572 is an abundant number, since it is smaller than the sum of its proper divisors (154671300).

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

81436572 is a wasteful number, since it uses less digits than its factorization.

81436572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1179 (or 1174 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 81436572 is about 9024.2214068583. The cubic root of 81436572 is about 433.4508191633.

The spelling of 81436572 in words is "eighty-one million, four hundred thirty-six thousand, five hundred seventy-two".