1211500000 has 84 divisors (see below), whose sum is σ = 2982618072. Its totient is φ = 484400000.

The previous prime is 1211499979. The next prime is 1211500039. The reversal of 1211500000 is 51121.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a self number, because there is not a number n which added to its sum of digits gives 1211500000.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 498789 + ... + 501211.

It is an arithmetic number, because the mean of its divisors is an integer number (35507358).

Almost surely, 2^1211500000 is an apocalyptic number.

1211500000 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 1211500000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1491309036).

1211500000 is an abundant number, since it is smaller than the sum of its proper divisors (1771118072).

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

1211500000 is an frugal number, since it uses more digits than its factorization.

1211500000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2463 (or 2430 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 10.

The square root of 1211500000 is about 34806.6085679142. The cubic root of 1211500000 is about 1066.0423864395.

Adding to 1211500000 its reverse (51121), we get a palindrome (1211551121).

The spelling of 1211500000 in words is "one billion, two hundred eleven million, five hundred thousand".