81042120 has 80 divisors (see below), whose sum is σ = 272402460. Its totient is φ = 21610368.

The previous prime is 81042119. The next prime is 81042187. The reversal of 81042120 is 2124018.

It can be written as a sum of positive squares in 2 ways, for example, as 74960964 + 6081156 = 8658^2 + 2466^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 81042093 and 81042102.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 9267 + ... + 15746.

Almost surely, 2^81042120 is an apocalyptic number.

It is an amenable number.

81042120 is an abundant number, since it is smaller than the sum of its proper divisors (191360340).

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

81042120 is a wasteful number, since it uses less digits than its factorization.

81042120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25036 (or 25023 counting only the distinct ones).

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

The square root of 81042120 is about 9002.3396958791. The cubic root of 81042120 is about 432.7498550742.

Adding to 81042120 its reverse (2124018), we get a palindrome (83166138).

The spelling of 81042120 in words is "eighty-one million, forty-two thousand, one hundred twenty".