1311997500 has 600 divisors, whose sum is σ = 5080373760. Its totient is φ = 291600000.

The previous prime is 1311997483. The next prime is 1311997507. The reversal of 1311997500 is 57991131.

1311997500 is a `hidden beast` number, since 131 + 19 + 9 + 7 + 500 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1311997507) by changing a digit.

It is a polite number, since it can be written in 199 ways as a sum of consecutive naturals, for example, 42322485 + ... + 42322515.

Almost surely, 2^1311997500 is an apocalyptic number.

1311997500 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 1311997500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2540186880).

1311997500 is an abundant number, since it is smaller than the sum of its proper divisors (3768376260).

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

1311997500 is a wasteful number, since it uses less digits than its factorization.

1311997500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97 (or 71 counting only the distinct ones).

The product of its (nonzero) digits is 8505, while the sum is 36.

The square root of 1311997500 is about 36221.5060426813. The cubic root of 1311997500 is about 1094.7400396209.

The spelling of 1311997500 in words is "one billion, three hundred eleven million, nine hundred ninety-seven thousand, five hundred".