1221004405 has 4 divisors (see below), whose sum is σ = 1465205292. Its totient is φ = 976803520.

The previous prime is 1221004387. The next prime is 1221004441. The reversal of 1221004405 is 5044001221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5044001221 = 7 ⋅720571603.

It can be written as a sum of positive squares in 2 ways, for example, as 212751396 + 1008253009 = 14586^2 + 31753^2 .

It is not a de Polignac number, because 1221004405 - 2¹³ = 1220996213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122100436 + ... + 122100445.

It is an arithmetic number, because the mean of its divisors is an integer number (366301323).

Almost surely, 2^1221004405 is an apocalyptic number.

It is an amenable number.

1221004405 is a deficient number, since it is larger than the sum of its proper divisors (244200887).

1221004405 is an equidigital number, since it uses as much as digits as its factorization.

1221004405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244200886.

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 1221004405 is about 34942.8734508197. The cubic root of 1221004405 is about 1068.8228837589.

Adding to 1221004405 its reverse (5044001221), we get a palindrome (6265005626).

The spelling of 1221004405 in words is "one billion, two hundred twenty-one million, four thousand, four hundred five".