218877021 has 18 divisors (see below), whose sum is σ = 347511710. Its totient is φ = 132652080.

The previous prime is 218877013. The next prime is 218877031. The reversal of 218877021 is 120778812.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 212751396 + 6125625 = 14586^2 + 2475^2 .

It is not a de Polignac number, because 218877021 - 2³ = 218877013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218877031) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 99406 + ... + 101583.

Almost surely, 2^218877021 is an apocalyptic number.

It is an amenable number.

218877021 is a deficient number, since it is larger than the sum of its proper divisors (128634689).

218877021 is a wasteful number, since it uses less digits than its factorization.

218877021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201017 (or 201003 counting only the distinct ones).

The product of its (nonzero) digits is 12544, while the sum is 36.

The square root of 218877021 is about 14794.4929281135. The cubic root of 218877021 is about 602.6521677370.

The spelling of 218877021 in words is "two hundred eighteen million, eight hundred seventy-seven thousand, twenty-one".