81137428 has 12 divisors (see below), whose sum is σ = 143027892. Its totient is φ = 40272320.

The previous prime is 81137377. The next prime is 81137453. The reversal of 81137428 is 82473118.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 30272004 + 50865424 = 5502^2 + 7132^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81137393 and 81137402.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 73483 + ... + 74578.

It is an arithmetic number, because the mean of its divisors is an integer number (11918991).

Almost surely, 2^81137428 is an apocalyptic number.

It is an amenable number.

81137428 is a deficient number, since it is larger than the sum of its proper divisors (61890464).

81137428 is a wasteful number, since it uses less digits than its factorization.

81137428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148202 (or 148200 counting only the distinct ones).

The product of its digits is 10752, while the sum is 34.

The square root of 81137428 is about 9007.6316532150. The cubic root of 81137428 is about 432.9194309501.

The spelling of 81137428 in words is "eighty-one million, one hundred thirty-seven thousand, four hundred twenty-eight".