181981400436 has 864 divisors, whose sum is σ = 593399439360. Its totient is φ = 48498912000.

The previous prime is 181981400431. The next prime is 181981400483. The reversal of 181981400436 is 634004189181.

181981400436 is a `hidden beast` number, since 18 + 198 + 1 + 400 + 43 + 6 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 181981400391 and 181981400400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181981400431) by changing a digit.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 2563118281 + ... + 2563118351.

Almost surely, 2^181981400436 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 181981400436, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (296699719680).

181981400436 is an abundant number, since it is smaller than the sum of its proper divisors (411418038924).

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

181981400436 is a wasteful number, since it uses less digits than its factorization.

181981400436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199 (or 174 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 45.

The spelling of 181981400436 in words is "one hundred eighty-one billion, nine hundred eighty-one million, four hundred thousand, four hundred thirty-six".