218581541 has 2 divisors, whose sum is σ = 218581542. Its totient is φ = 218581540.

The previous prime is 218581507. The next prime is 218581543. The reversal of 218581541 is 145185812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 209641441 + 8940100 = 14479^2 + 2990^2 .

It is a cyclic number.

It is not a de Polignac number, because 218581541 - 2²⁶ = 151472677 is a prime.

Together with 218581543, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218581543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109290770 + 109290771.

It is an arithmetic number, because the mean of its divisors is an integer number (109290771).

Almost surely, 2^218581541 is an apocalyptic number.

It is an amenable number.

218581541 is a deficient number, since it is larger than the sum of its proper divisors (1).

218581541 is an equidigital number, since it uses as much as digits as its factorization.

218581541 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12800, while the sum is 35.

The square root of 218581541 is about 14784.5034072843. The cubic root of 218581541 is about 602.3808557875.

The spelling of 218581541 in words is "two hundred eighteen million, five hundred eighty-one thousand, five hundred forty-one".