221431406 has 36 divisors (see below), whose sum is σ = 393133464. Its totient is φ = 91630080.

The previous prime is 221431367. The next prime is 221431423. The reversal of 221431406 is 604134122.

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 17 ways as a sum of consecutive naturals, for example, 2282750 + ... + 2282846.

It is an arithmetic number, because the mean of its divisors is an integer number (10920374).

Almost surely, 2^221431406 is an apocalyptic number.

221431406 is a deficient number, since it is larger than the sum of its proper divisors (171702058).

221431406 is an frugal number, since it uses more digits than its factorization.

221431406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285 (or 147 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 221431406 is about 14880.5714272000. The cubic root of 221431406 is about 604.9875060599.

Adding to 221431406 its reverse (604134122), we get a palindrome (825565528).

The spelling of 221431406 in words is "two hundred twenty-one million, four hundred thirty-one thousand, four hundred six".