1211566720 has 256 divisors, whose sum is σ = 3627348480. Its totient is φ = 376750080.

The previous prime is 1211566703. The next prime is 1211566729. The reversal of 1211566720 is 276651121.

It is not an unprimeable number, because it can be changed into a prime (1211566729) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4134894 + ... + 4135186.

It is an arithmetic number, because the mean of its divisors is an integer number (14169330).

Almost surely, 2^1211566720 is an apocalyptic number.

1211566720 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 1211566720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1813674240).

1211566720 is an abundant number, since it is smaller than the sum of its proper divisors (2415781760).

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

1211566720 is a wasteful number, since it uses less digits than its factorization.

1211566720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403 (or 391 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 31.

The square root of 1211566720 is about 34807.5669933996. The cubic root of 1211566720 is about 1066.0619558554.

The spelling of 1211566720 in words is "one billion, two hundred eleven million, five hundred sixty-six thousand, seven hundred twenty".