1211545500 has 192 divisors, whose sum is σ = 3892202496. Its totient is φ = 290400000.

The previous prime is 1211545481. The next prime is 1211545537. The reversal of 1211545500 is 55451121.

1211545500 is digitally balanced in base 4 and base 6, because in such bases it contains all the possibile digits an equal number of times.

It is a congruent number.

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, 1666137 + ... + 1666863.

It is an arithmetic number, because the mean of its divisors is an integer number (20271888).

Almost surely, 2^1211545500 is an apocalyptic number.

1211545500 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 1211545500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1946101248).

1211545500 is an abundant number, since it is smaller than the sum of its proper divisors (2680656996).

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

1211545500 is a wasteful number, since it uses less digits than its factorization.

1211545500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 861 (or 849 counting only the distinct ones).

The product of its (nonzero) digits is 1000, while the sum is 24.

The square root of 1211545500 is about 34807.2621732879. The cubic root of 1211545500 is about 1066.0557319674.

Adding to 1211545500 its reverse (55451121), we get a palindrome (1266996621).

The spelling of 1211545500 in words is "one billion, two hundred eleven million, five hundred forty-five thousand, five hundred".