81801252 has 60 divisors (see below), whose sum is σ = 230306076. Its totient is φ = 25168320.

The previous prime is 81801221. The next prime is 81801253. The reversal of 81801252 is 25210818.

It can be written as a sum of positive squares in 2 ways, for example, as 51065316 + 30735936 = 7146^2 + 5544^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (81801253) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 5499 + ... + 13922.

Almost surely, 2^81801252 is an apocalyptic number.

It is an amenable number.

81801252 is an abundant number, since it is smaller than the sum of its proper divisors (148504824).

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

81801252 is a wasteful number, since it uses less digits than its factorization.

81801252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19450 (or 19439 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 81801252 is about 9044.4044580061. The cubic root of 81801252 is about 434.0968658329.

The spelling of 81801252 in words is "eighty-one million, eight hundred one thousand, two hundred fifty-two".