81245340 has 144 divisors (see below), whose sum is σ = 276363360. Its totient is φ = 19146240.

The previous prime is 81245323. The next prime is 81245347. The reversal of 81245340 is 4354218.

81245340 is a `hidden beast` number, since 8 + 124 + 534 + 0 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81245347) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 72706 + ... + 73814.

It is an arithmetic number, because the mean of its divisors is an integer number (1919190).

Almost surely, 2^81245340 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 81245340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (138181680).

81245340 is an abundant number, since it is smaller than the sum of its proper divisors (195118020).

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

81245340 is a wasteful number, since it uses less digits than its factorization.

81245340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1172 (or 1167 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 81245340 is about 9013.6196946621. The cubic root of 81245340 is about 433.1112721547. Note that the first 3 decimals are identical.

Adding to 81245340 its reverse (4354218), we get a palindrome (85599558).

The spelling of 81245340 in words is "eighty-one million, two hundred forty-five thousand, three hundred forty".