81213144 has 64 divisors (see below), whose sum is σ = 214896000. Its totient is φ = 25505280.

The previous prime is 81213127. The next prime is 81213151. The reversal of 81213144 is 44131218.

It is a Harshad number since it is a multiple of its sum of digits (24).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 109527 + ... + 110265.

It is an arithmetic number, because the mean of its divisors is an integer number (3357750).

Almost surely, 2^81213144 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 81213144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (107448000).

81213144 is an abundant number, since it is smaller than the sum of its proper divisors (133682856).

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

81213144 is a wasteful number, since it uses less digits than its factorization.

81213144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1008 (or 1004 counting only the distinct ones).

The product of its digits is 768, while the sum is 24.

The square root of 81213144 is about 9011.8335537226. The cubic root of 81213144 is about 433.0540533124.

It can be divided in two parts, 812131 and 44, that added together give a triangular number (812175 = T₁₂₇₄).

The spelling of 81213144 in words is "eighty-one million, two hundred thirteen thousand, one hundred forty-four".