81201240 has 96 divisors (see below), whose sum is σ = 265402800. Its totient is φ = 21530880.

The previous prime is 81201229. The next prime is 81201257. The reversal of 81201240 is 4210218.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 75426 + ... + 76494.

Almost surely, 2^81201240 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 81201240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132701400).

81201240 is an abundant number, since it is smaller than the sum of its proper divisors (184201560).

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

81201240 is a wasteful number, since it uses less digits than its factorization.

81201240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1297 (or 1290 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 81201240 is about 9011.1730645904. The cubic root of 81201240 is about 433.0328936532.

Adding to 81201240 its reverse (4210218), we get a palindrome (85411458).

The spelling of 81201240 in words is "eighty-one million, two hundred one thousand, two hundred forty".