1291291920 has 120 divisors (see below), whose sum is σ = 4407830232. Its totient is φ = 338688000.

The previous prime is 1291291913. The next prime is 1291291951. The reversal of 1291291920 is 291921921.

It can be written as a sum of positive squares in 4 ways, for example, as 52533504 + 1238758416 = 7248^2 + 35196^2 .

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 29220 + ... + 58620.

Almost surely, 2^1291291920 is an apocalyptic number.

1291291920 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 1291291920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2203915116).

1291291920 is an abundant number, since it is smaller than the sum of its proper divisors (3116538312).

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

1291291920 is a wasteful number, since it uses less digits than its factorization.

1291291920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29481 (or 29472 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 36.

The square root of 1291291920 is about 35934.5505050502. The cubic root of 1291291920 is about 1088.9505146914.

The spelling of 1291291920 in words is "one billion, two hundred ninety-one million, two hundred ninety-one thousand, nine hundred twenty".