1311581920 has 144 divisors (see below), whose sum is σ = 3499874784. Its totient is φ = 463795200.

The previous prime is 1311581903. The next prime is 1311581939. The reversal of 1311581920 is 291851131.

It is a congruent number.

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, 715405 + ... + 717235.

It is an arithmetic number, because the mean of its divisors is an integer number (24304686).

Almost surely, 2^1311581920 is an apocalyptic number.

1311581920 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 1311581920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1749937392).

1311581920 is an abundant number, since it is smaller than the sum of its proper divisors (2188292864).

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

1311581920 is a wasteful number, since it uses less digits than its factorization.

1311581920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1905 (or 1886 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 31.

The square root of 1311581920 is about 36215.7689411671. The cubic root of 1311581920 is about 1094.6244397791.

The spelling of 1311581920 in words is "one billion, three hundred eleven million, five hundred eighty-one thousand, nine hundred twenty".