81142120 has 32 divisors (see below), whose sum is σ = 183181320. Its totient is φ = 32348160.

The previous prime is 81142111. The next prime is 81142129. The reversal of 81142120 is 2124118.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81142111) and next prime (81142129).

It can be written as a sum of positive squares in 4 ways, for example, as 60000516 + 21141604 = 7746^2 + 4598^2 .

It is not an unprimeable number, because it can be changed into a prime (81142129) by changing a digit.

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, 9280 + ... + 15760.

Almost surely, 2^81142120 is an apocalyptic number.

It is an amenable number.

81142120 is an abundant number, since it is smaller than the sum of its proper divisors (102039200).

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

81142120 is a wasteful number, since it uses less digits than its factorization.

81142120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6805 (or 6801 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 81142120 is about 9007.8920952685. The cubic root of 81142120 is about 432.9277757172.

Adding to 81142120 its reverse (2124118), we get a palindrome (83266238).

The spelling of 81142120 in words is "eighty-one million, one hundred forty-two thousand, one hundred twenty".