81690252 has 96 divisors (see below), whose sum is σ = 225792000. Its totient is φ = 22974336.

The previous prime is 81690247. The next prime is 81690269. The reversal of 81690252 is 25209618.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 366213 + ... + 366435.

It is an arithmetic number, because the mean of its divisors is an integer number (2352000).

Almost surely, 2^81690252 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81690252, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (112896000).

81690252 is an abundant number, since it is smaller than the sum of its proper divisors (144101748).

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

81690252 is a wasteful number, since it uses less digits than its factorization.

81690252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340 (or 324 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 81690252 is about 9038.2659841366. The cubic root of 81690252 is about 433.9004280763.

The spelling of 81690252 in words is "eighty-one million, six hundred ninety thousand, two hundred fifty-two".