81521838 has 24 divisors (see below), whose sum is σ = 178869600. Its totient is φ = 26829504.

The previous prime is 81521831. The next prime is 81521873. The reversal of 81521838 is 83812518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81521831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27243 + ... + 30086.

It is an arithmetic number, because the mean of its divisors is an integer number (7452900).

Almost surely, 2^81521838 is an apocalyptic number.

81521838 is an abundant number, since it is smaller than the sum of its proper divisors (97347762).

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

81521838 is a wasteful number, since it uses less digits than its factorization.

81521838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57416 (or 57413 counting only the distinct ones).

The product of its digits is 15360, while the sum is 36.

The square root of 81521838 is about 9028.9444565796. The cubic root of 81521838 is about 433.6020441199.

The spelling of 81521838 in words is "eighty-one million, five hundred twenty-one thousand, eight hundred thirty-eight".