81851400 has 144 divisors (see below), whose sum is σ = 282543300. Its totient is φ = 21219840.

The previous prime is 81851387. The next prime is 81851417. The reversal of 81851400 is 415818.

It can be written as a sum of positive squares in 6 ways, for example, as 71470116 + 10381284 = 8454^2 + 3222^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 65986 + ... + 67214.

Almost surely, 2^81851400 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 81851400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (141271650).

81851400 is an abundant number, since it is smaller than the sum of its proper divisors (200691900).

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

81851400 is a wasteful number, since it uses less digits than its factorization.

81851400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1288 (or 1276 counting only the distinct ones).

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

The square root of 81851400 is about 9047.1763550845. The cubic root of 81851400 is about 434.1855549508.

The spelling of 81851400 in words is "eighty-one million, eight hundred fifty-one thousand, four hundred".