1561221306 has 48 divisors (see below), whose sum is σ = 3407033448. Its totient is φ = 516672000.

The previous prime is 1561221281. The next prime is 1561221307. The reversal of 1561221306 is 6031221651.

1561221306 is a `hidden beast` number, since 15 + 612 + 2 + 1 + 30 + 6 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1209996225 + 351225081 = 34785^2 + 18741^2 .

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1561221306.

It is not an unprimeable number, because it can be changed into a prime (1561221307) 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, 2597406 + ... + 2598006.

Almost surely, 2^1561221306 is an apocalyptic number.

1561221306 is an abundant number, since it is smaller than the sum of its proper divisors (1845812142).

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

1561221306 is a wasteful number, since it uses less digits than its factorization.

1561221306 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1407 (or 1404 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 1561221306 is about 39512.2930997430. The cubic root of 1561221306 is about 1160.0805795193.

Adding to 1561221306 its reverse (6031221651), we get a palindrome (7592442957).

The spelling of 1561221306 in words is "one billion, five hundred sixty-one million, two hundred twenty-one thousand, three hundred six".