81340040 has 32 divisors (see below), whose sum is σ = 183294360. Its totient is φ = 32486400.

The previous prime is 81339997. The next prime is 81340069. The reversal of 81340040 is 4004318.

It can be written as a sum of positive squares in 4 ways, for example, as 72352036 + 8988004 = 8506^2 + 2998^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 81339994 and 81340021.

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 7 ways as a sum of consecutive naturals, for example, 36560 + ... + 38720.

Almost surely, 2^81340040 is an apocalyptic number.

It is an amenable number.

81340040 is an abundant number, since it is smaller than the sum of its proper divisors (101954320).

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

81340040 is a wasteful number, since it uses less digits than its factorization.

81340040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3113 (or 3109 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 81340040 is about 9018.8713262802. The cubic root of 81340040 is about 433.2794857482.

Adding to 81340040 its reverse (4004318), we get a palindrome (85344358).

The spelling of 81340040 in words is "eighty-one million, three hundred forty thousand, forty".