81809252 has 24 divisors (see below), whose sum is σ = 170733696. Its totient is φ = 33536448.

The previous prime is 81809251. The next prime is 81809291. The reversal of 81809252 is 25290818.

It is not an unprimeable number, because it can be changed into a prime (81809251) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62873 + ... + 64160.

It is an arithmetic number, because the mean of its divisors is an integer number (7113904).

Almost surely, 2^81809252 is an apocalyptic number.

It is an amenable number.

81809252 is an abundant number, since it is smaller than the sum of its proper divisors (88924444).

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

81809252 is a wasteful number, since it uses less digits than its factorization.

81809252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127067 (or 127065 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 35.

The square root of 81809252 is about 9044.8467095910. The cubic root of 81809252 is about 434.1110166420. Note that the first 3 decimals are identical.

The spelling of 81809252 in words is "eighty-one million, eight hundred nine thousand, two hundred fifty-two".