1261443220 has 48 divisors (see below), whose sum is σ = 2731170960. Its totient is φ = 489037824.

The previous prime is 1261443203. The next prime is 1261443221. The reversal of 1261443220 is 223441621.

It is a happy number.

1261443220 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 8 ways, for example, as 41757444 + 1219685776 = 6462^2 + 34924^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261443221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 195892 + ... + 202228.

It is an arithmetic number, because the mean of its divisors is an integer number (56899395).

Almost surely, 2^1261443220 is an apocalyptic number.

1261443220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1261443220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1365585480).

1261443220 is an abundant number, since it is smaller than the sum of its proper divisors (1469727740).

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

1261443220 is a wasteful number, since it uses less digits than its factorization.

1261443220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6652 (or 6650 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 1261443220 is about 35516.8019393639. The cubic root of 1261443220 is about 1080.4945209002.

Adding to 1261443220 its reverse (223441621), we get a palindrome (1484884841).

The spelling of 1261443220 in words is "one billion, two hundred sixty-one million, four hundred forty-three thousand, two hundred twenty".