218855021 has 24 divisors (see below), whose sum is σ = 279673920. Its totient is φ = 169344000.

The previous prime is 218855011. The next prime is 218855023. The reversal of 218855021 is 120558812.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-218855021 is a prime.

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 (218855023) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 80045 + ... + 82733.

It is an arithmetic number, because the mean of its divisors is an integer number (11653080).

Almost surely, 2^218855021 is an apocalyptic number.

It is an amenable number.

218855021 is a deficient number, since it is larger than the sum of its proper divisors (60818899).

218855021 is a wasteful number, since it uses less digits than its factorization.

218855021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2865 (or 2858 counting only the distinct ones).

The product of its (nonzero) digits is 6400, while the sum is 32.

The square root of 218855021 is about 14793.7493895226. The cubic root of 218855021 is about 602.6319755885.

The spelling of 218855021 in words is "two hundred eighteen million, eight hundred fifty-five thousand, twenty-one".