181221534 has 48 divisors (see below), whose sum is σ = 424569600. Its totient is φ = 55533888.

The previous prime is 181221529. The next prime is 181221541. The reversal of 181221534 is 435122181.

181221534 is a `hidden beast` number, since 1 + 8 + 122 + 1 + 534 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 181221498 and 181221507.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 61507 + ... + 64385.

It is an arithmetic number, because the mean of its divisors is an integer number (8845200).

Almost surely, 2^181221534 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 181221534, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (212284800).

181221534 is an abundant number, since it is smaller than the sum of its proper divisors (243348066).

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

181221534 is a wasteful number, since it uses less digits than its factorization.

181221534 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3169 (or 3166 counting only the distinct ones).

The product of its digits is 1920, while the sum is 27.

The square root of 181221534 is about 13461.8547756243. The cubic root of 181221534 is about 565.8959695097.

The spelling of 181221534 in words is "one hundred eighty-one million, two hundred twenty-one thousand, five hundred thirty-four".