221218424 has 32 divisors (see below), whose sum is σ = 474520800. Its totient is φ = 94711680.

The previous prime is 221218423. The next prime is 221218427. The reversal of 221218424 is 424812122.

It is a super-2 number, since 2×221218424² = 97875182234087552, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 221218393 and 221218402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221218423) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 96362 + ... + 98630.

It is an arithmetic number, because the mean of its divisors is an integer number (14828775).

Almost surely, 2^221218424 is an apocalyptic number.

It is an amenable number.

221218424 is an abundant number, since it is smaller than the sum of its proper divisors (253302376).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221218424 is a wasteful number, since it uses less digits than its factorization.

221218424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4023 (or 4019 counting only the distinct ones).

The product of its digits is 2048, while the sum is 26.

The square root of 221218424 is about 14873.4133271418. The cubic root of 221218424 is about 604.7934763977.

The spelling of 221218424 in words is "two hundred twenty-one million, two hundred eighteen thousand, four hundred twenty-four".