81513144 has 48 divisors (see below), whose sum is σ = 222201720. Its totient is φ = 26994240.

The previous prime is 81513139. The next prime is 81513149. The reversal of 81513144 is 44131518.

It is a happy number.

81513144 is a `hidden beast` number, since 8 + 1 + 513 + 144 = 666.

It is an interprime number because it is at equal distance from previous prime (81513139) and next prime (81513149).

It is a super-3 number, since 3×81513144³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81513149) 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, 7699 + ... + 14909.

Almost surely, 2^81513144 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 81513144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (111100860).

81513144 is an abundant number, since it is smaller than the sum of its proper divisors (140688576).

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

81513144 is a wasteful number, since it uses less digits than its factorization.

81513144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7380 (or 7373 counting only the distinct ones).

The product of its digits is 1920, while the sum is 27.

The square root of 81513144 is about 9028.4629921155. The cubic root of 81513144 is about 433.5866295583.

The spelling of 81513144 in words is "eighty-one million, five hundred thirteen thousand, one hundred forty-four".