1291041220 has 72 divisors (see below), whose sum is σ = 3162521880. Its totient is φ = 441423360.

The previous prime is 1291041211. The next prime is 1291041223. The reversal of 1291041220 is 221401921.

It can be written as a sum of positive squares in 4 ways, for example, as 547279236 + 743761984 = 23394^2 + 27272^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1291041191 and 1291041200.

It is not an unprimeable number, because it can be changed into a prime (1291041223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 399210 + ... + 402430.

It is an arithmetic number, because the mean of its divisors is an integer number (43923915).

Almost surely, 2^1291041220 is an apocalyptic number.

1291041220 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 1291041220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1581260940).

1291041220 is an abundant number, since it is smaller than the sum of its proper divisors (1871480660).

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

1291041220 is a wasteful number, since it uses less digits than its factorization.

1291041220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3653 (or 3644 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 1291041220 is about 35931.0620494302. The cubic root of 1291041220 is about 1088.8800380989.

The spelling of 1291041220 in words is "one billion, two hundred ninety-one million, forty-one thousand, two hundred twenty".