81245540 has 24 divisors (see below), whose sum is σ = 173164992. Its totient is φ = 32012640.

The previous prime is 81245509. The next prime is 81245543. The reversal of 81245540 is 4554218.

It is not an unprimeable number, because it can be changed into a prime (81245543) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28976 + ... + 31655.

It is an arithmetic number, because the mean of its divisors is an integer number (7215208).

Almost surely, 2^81245540 is an apocalyptic number.

It is an amenable number.

81245540 is an abundant number, since it is smaller than the sum of its proper divisors (91919452).

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

81245540 is a wasteful number, since it uses less digits than its factorization.

81245540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60707 (or 60705 counting only the distinct ones).

The product of its (nonzero) digits is 6400, while the sum is 29.

The square root of 81245540 is about 9013.6307889773. The cubic root of 81245540 is about 433.1116275482. Note that the first 3 decimals are identical.

Adding to 81245540 its reverse (4554218), we get a palindrome (85799758).

The spelling of 81245540 in words is "eighty-one million, two hundred forty-five thousand, five hundred forty".