81122540 has 24 divisors (see below), whose sum is σ = 172413360. Its totient is φ = 32057408.

The previous prime is 81122539. The next prime is 81122551. The reversal of 81122540 is 4522118.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22775 + ... + 26094.

It is an arithmetic number, because the mean of its divisors is an integer number (7183890).

Almost surely, 2^81122540 is an apocalyptic number.

It is an amenable number.

81122540 is an abundant number, since it is smaller than the sum of its proper divisors (91290820).

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

81122540 is a wasteful number, since it uses less digits than its factorization.

81122540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48961 (or 48959 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 81122540 is about 9006.8052049548. The cubic root of 81122540 is about 432.8929503690.

Adding to 81122540 its reverse (4522118), we get a palindrome (85644658).

It can be divided in two parts, 81 and 122540, that multiplied together give a triangular number (9925740 = T₄₄₅₅).

The spelling of 81122540 in words is "eighty-one million, one hundred twenty-two thousand, five hundred forty".