218977421 has 4 divisors (see below), whose sum is σ = 235821852. Its totient is φ = 202132992.

The previous prime is 218977417. The next prime is 218977441. The reversal of 218977421 is 124779812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 43414921 + 175562500 = 6589^2 + 13250^2 .

It is a cyclic number.

It is not a de Polignac number, because 218977421 - 2² = 218977417 is a prime.

It is a super-2 number, since 2×218977421² = 95902221815622482, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218977441) 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 in 3 ways as a sum of consecutive naturals, for example, 8422196 + ... + 8422221.

It is an arithmetic number, because the mean of its divisors is an integer number (58955463).

Almost surely, 2^218977421 is an apocalyptic number.

It is an amenable number.

218977421 is a deficient number, since it is larger than the sum of its proper divisors (16844431).

218977421 is a wasteful number, since it uses less digits than its factorization.

218977421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16844430.

The product of its digits is 56448, while the sum is 41.

The square root of 218977421 is about 14797.8856935712. The cubic root of 218977421 is about 602.7443001869.

The spelling of 218977421 in words is "two hundred eighteen million, nine hundred seventy-seven thousand, four hundred twenty-one".