1216818720 has 384 divisors, whose sum is σ = 4694215680. Its totient is φ = 292515840.

The previous prime is 1216818709. The next prime is 1216818721. The reversal of 1216818720 is 278186121.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216818721) by changing a digit.

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 63 ways as a sum of consecutive naturals, for example, 2639290 + ... + 2639750.

It is an arithmetic number, because the mean of its divisors is an integer number (12224520).

Almost surely, 2^1216818720 is an apocalyptic number.

1216818720 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 1216818720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2347107840).

1216818720 is an abundant number, since it is smaller than the sum of its proper divisors (3477396960).

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

1216818720 is a wasteful number, since it uses less digits than its factorization.

1216818720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 545 (or 531 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The square root of 1216818720 is about 34882.9287761220. The cubic root of 1216818720 is about 1067.6001533128.

The spelling of 1216818720 in words is "one billion, two hundred sixteen million, eight hundred eighteen thousand, seven hundred twenty".