221406210 has 80 divisors (see below), whose sum is σ = 605231352. Its totient is φ = 58060800.

The previous prime is 221406209. The next prime is 221406217. The reversal of 221406210 is 12604122.

221406210 is a `hidden beast` number, since 2 + 2 + 1 + 40 + 621 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 147841281 + 73564929 = 12159^2 + 8577^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (221406217) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 47170 + ... + 51650.

Almost surely, 2^221406210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221406210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (302615676).

221406210 is an abundant number, since it is smaller than the sum of its proper divisors (383825142).

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

221406210 is a wasteful number, since it uses less digits than its factorization.

221406210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4561 (or 4552 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 221406210 is about 14879.7247958422. The cubic root of 221406210 is about 604.9645586324.

The spelling of 221406210 in words is "two hundred twenty-one million, four hundred six thousand, two hundred ten".