221040405 has 24 divisors (see below), whose sum is σ = 393494712. Its totient is φ = 114701184.

The previous prime is 221040403. The next prime is 221040427. The reversal of 221040405 is 504040122.

221040405 is a `hidden beast` number, since 221 + 0 + 40 + 405 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 7851204 + 213189201 = 2802^2 + 14601^2 .

It is not a de Polignac number, because 221040405 - 2¹ = 221040403 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221040401) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 64714 + ... + 68043.

It is an arithmetic number, because the mean of its divisors is an integer number (16395613).

Almost surely, 2^221040405 is an apocalyptic number.

It is an amenable number.

221040405 is a deficient number, since it is larger than the sum of its proper divisors (172454307).

221040405 is a wasteful number, since it uses less digits than its factorization.

221040405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132805 (or 132802 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 221040405 is about 14867.4276524219. The cubic root of 221040405 is about 604.6312029595.

Adding to 221040405 its reverse (504040122), we get a palindrome (725080527).

It can be divided in two parts, 221040 and 405, that added together give a triangular number (221445 = T₆₆₅).

The spelling of 221040405 in words is "two hundred twenty-one million, forty thousand, four hundred five".