181355993 has 16 divisors (see below), whose sum is σ = 223539456. Its totient is φ = 143277120.

The previous prime is 181355987. The next prime is 181356001. The reversal of 181355993 is 399553181.

It is not a de Polignac number, because 181355993 - 2¹⁰ = 181354969 is a prime.

It is not an unprimeable number, because it can be changed into a prime (181355393) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 92855 + ... + 94787.

It is an arithmetic number, because the mean of its divisors is an integer number (13971216).

Almost surely, 2^181355993 is an apocalyptic number.

181355993 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

181355993 is a deficient number, since it is larger than the sum of its proper divisors (42183463).

181355993 is a wasteful number, since it uses less digits than its factorization.

181355993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2984.

The product of its digits is 145800, while the sum is 44.

The square root of 181355993 is about 13466.8479236977. The cubic root of 181355993 is about 566.0358921663.

The spelling of 181355993 in words is "one hundred eighty-one million, three hundred fifty-five thousand, nine hundred ninety-three".