1311521640 has 256 divisors, whose sum is σ = 4824852480. Its totient is φ = 280642560.

The previous prime is 1311521633. The next prime is 1311521689. The reversal of 1311521640 is 461251131.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 1311521640.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 393019 + ... + 396341.

It is an arithmetic number, because the mean of its divisors is an integer number (18847080).

Almost surely, 2^1311521640 is an apocalyptic number.

1311521640 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 1311521640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2412426240).

1311521640 is an abundant number, since it is smaller than the sum of its proper divisors (3513330840).

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

1311521640 is a wasteful number, since it uses less digits than its factorization.

1311521640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3384 (or 3380 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 1311521640 is about 36214.9366974457. The cubic root of 1311521640 is about 1094.6076699607.

Adding to 1311521640 its reverse (461251131), we get a palindrome (1772772771).

The spelling of 1311521640 in words is "one billion, three hundred eleven million, five hundred twenty-one thousand, six hundred forty".