1211976780 has 240 divisors, whose sum is σ = 4065707520. Its totient is φ = 269614464.

The previous prime is 1211976737. The next prime is 1211976793. The reversal of 1211976780 is 876791121.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 6770731 + ... + 6770909.

It is an arithmetic number, because the mean of its divisors is an integer number (16940448).

Almost surely, 2^1211976780 is an apocalyptic number.

1211976780 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 1211976780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2032853760).

1211976780 is an abundant number, since it is smaller than the sum of its proper divisors (2853730740).

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

1211976780 is a wasteful number, since it uses less digits than its factorization.

1211976780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 266 (or 243 counting only the distinct ones).

The product of its (nonzero) digits is 42336, while the sum is 42.

The square root of 1211976780 is about 34813.4568809247. The cubic root of 1211976780 is about 1066.1822133835.

The spelling of 1211976780 in words is "one billion, two hundred eleven million, nine hundred seventy-six thousand, seven hundred eighty".