221390406 has 48 divisors (see below), whose sum is σ = 507282048. Its totient is φ = 69667200.

The previous prime is 221390399. The next prime is 221390419. The reversal of 221390406 is 604093122.

221390406 is a `hidden beast` number, since 221 + 39 + 0 + 406 = 666.

221390406 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 221390406.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18040 + ... + 27716.

It is an arithmetic number, because the mean of its divisors is an integer number (10568376).

Almost surely, 2^221390406 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221390406, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (253641024).

221390406 is an abundant number, since it is smaller than the sum of its proper divisors (285891642).

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

221390406 is a wasteful number, since it uses less digits than its factorization.

221390406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9757 (or 9754 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 221390406 is about 14879.1937281561. The cubic root of 221390406 is about 604.9501641439.

The spelling of 221390406 in words is "two hundred twenty-one million, three hundred ninety thousand, four hundred six".