1311021000 has 384 divisors, whose sum is σ = 4734812160. Its totient is φ = 326592000.

The previous prime is 1311020987. The next prime is 1311021001. The reversal of 1311021000 is 1201131.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (1311021001) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 10322937 + ... + 10323063.

It is an arithmetic number, because the mean of its divisors is an integer number (12330240).

Almost surely, 2^1311021000 is an apocalyptic number.

1311021000 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 1311021000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2367406080).

1311021000 is an abundant number, since it is smaller than the sum of its proper divisors (3423791160).

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

1311021000 is a wasteful number, since it uses less digits than its factorization.

1311021000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222 (or 205 counting only the distinct ones).

The product of its (nonzero) digits is 6, while the sum is 9.

The square root of 1311021000 is about 36208.0239725948. The cubic root of 1311021000 is about 1094.4683726969.

Adding to 1311021000 its reverse (1201131), we get a palindrome (1312222131).

The spelling of 1311021000 in words is "one billion, three hundred eleven million, twenty-one thousand".