1291211540 has 72 divisors (see below), whose sum is σ = 2904760320. Its totient is φ = 482001408.

The previous prime is 1291211539. The next prime is 1291211543. The reversal of 1291211540 is 451121921.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1291211543) 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, 733181 + ... + 734939.

Almost surely, 2^1291211540 is an apocalyptic number.

1291211540 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 1291211540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1452380160).

1291211540 is an abundant number, since it is smaller than the sum of its proper divisors (1613548780).

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

1291211540 is a wasteful number, since it uses less digits than its factorization.

1291211540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1929 (or 1910 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 1291211540 is about 35933.4320654179. The cubic root of 1291211540 is about 1088.9279193207.

The spelling of 1291211540 in words is "one billion, two hundred ninety-one million, two hundred eleven thousand, five hundred forty".