1261335220 has 24 divisors (see below), whose sum is σ = 2651658408. Its totient is φ = 503990400.

The previous prime is 1261335199. The next prime is 1261335221. The reversal of 1261335220 is 225331621.

It can be written as a sum of positive squares in 4 ways, for example, as 30869136 + 1230466084 = 5556^2 + 35078^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261335221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14691 + ... + 52330.

It is an arithmetic number, because the mean of its divisors is an integer number (110485767).

Almost surely, 2^1261335220 is an apocalyptic number.

1261335220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1261335220 is an abundant number, since it is smaller than the sum of its proper divisors (1390323188).

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

1261335220 is a wasteful number, since it uses less digits than its factorization.

1261335220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67971 (or 67969 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 1261335220 is about 35515.2814996587. The cubic root of 1261335220 is about 1080.4636840680.

Adding to 1261335220 its reverse (225331621), we get a palindrome (1486666841).

The spelling of 1261335220 in words is "one billion, two hundred sixty-one million, three hundred thirty-five thousand, two hundred twenty".