81142540 has 24 divisors (see below), whose sum is σ = 179368560. Its totient is φ = 30748608.

The previous prime is 81142519. The next prime is 81142553. The reversal of 81142540 is 4524118.

It is a super-2 number, since 2×81142540² = 13168223595303200, which contains 22 as substring.

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, 106387 + ... + 107146.

It is an arithmetic number, because the mean of its divisors is an integer number (7473690).

Almost surely, 2^81142540 is an apocalyptic number.

It is an amenable number.

81142540 is an abundant number, since it is smaller than the sum of its proper divisors (98226020).

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

81142540 is a wasteful number, since it uses less digits than its factorization.

81142540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213561 (or 213559 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 25.

The square root of 81142540 is about 9007.9154081286. The cubic root of 81142540 is about 432.9285226756.

Adding to 81142540 its reverse (4524118), we get a palindrome (85666658).

The spelling of 81142540 in words is "eighty-one million, one hundred forty-two thousand, five hundred forty".