218413621 has 2 divisors, whose sum is σ = 218413622. Its totient is φ = 218413620.

The previous prime is 218413579. The next prime is 218413633. The reversal of 218413621 is 126314812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 187388721 + 31024900 = 13689^2 + 5570^2 .

It is a cyclic number.

It is not a de Polignac number, because 218413621 - 2²¹ = 216316469 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 218413621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218413651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109206810 + 109206811.

It is an arithmetic number, because the mean of its divisors is an integer number (109206811).

Almost surely, 2^218413621 is an apocalyptic number.

It is an amenable number.

218413621 is a deficient number, since it is larger than the sum of its proper divisors (1).

218413621 is an equidigital number, since it uses as much as digits as its factorization.

218413621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2304, while the sum is 28.

The square root of 218413621 is about 14778.8233970097. The cubic root of 218413621 is about 602.2265614124.

The spelling of 218413621 in words is "two hundred eighteen million, four hundred thirteen thousand, six hundred twenty-one".