221420406 has 16 divisors (see below), whose sum is σ = 444567024. Its totient is φ = 73519104.

The previous prime is 221420399. The next prime is 221420411. The reversal of 221420406 is 604024122.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 70255 + ... + 73338.

It is an arithmetic number, because the mean of its divisors is an integer number (27785439).

Almost surely, 2^221420406 is an apocalyptic number.

221420406 is an abundant number, since it is smaller than the sum of its proper divisors (223146618).

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

221420406 is a wasteful number, since it uses less digits than its factorization.

221420406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143855.

The product of its (nonzero) digits is 768, while the sum is 21.

The square root of 221420406 is about 14880.2018131476. The cubic root of 221420406 is about 604.9774879495.

Adding to 221420406 its reverse (604024122), we get a palindrome (825444528).

The spelling of 221420406 in words is "two hundred twenty-one million, four hundred twenty thousand, four hundred six".