21058218 has 40 divisors (see below), whose sum is σ = 48299328. Its totient is φ = 6853896.

The previous prime is 21058211. The next prime is 21058241. The reversal of 21058218 is 81285012.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21058191 and 21058200.

It is not an unprimeable number, because it can be changed into a prime (21058211) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 5455 + ... + 8477.

Almost surely, 2^21058218 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21058218, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24149664).

21058218 is an abundant number, since it is smaller than the sum of its proper divisors (27241110).

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

21058218 is a wasteful number, since it uses less digits than its factorization.

21058218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3080 (or 3071 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 21058218 is about 4588.9234031524. The cubic root of 21058218 is about 276.1471332708.

The spelling of 21058218 in words is "twenty-one million, fifty-eight thousand, two hundred eighteen".