1216615400 has 384 divisors, whose sum is σ = 3899750400. Its totient is φ = 340761600.

The previous prime is 1216615343. The next prime is 1216615441. The reversal of 1216615400 is 45166121.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 1216615400.

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 95 ways as a sum of consecutive naturals, for example, 11811749 + ... + 11811851.

It is an arithmetic number, because the mean of its divisors is an integer number (10155600).

Almost surely, 2^1216615400 is an apocalyptic number.

1216615400 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 1216615400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1949875200).

1216615400 is an abundant number, since it is smaller than the sum of its proper divisors (2683135000).

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

1216615400 is a wasteful number, since it uses less digits than its factorization.

1216615400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209 (or 200 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 1216615400 is about 34880.0143348594. The cubic root of 1216615400 is about 1067.5406877160.

It can be divided in two parts, 1216 and 615400, that added together give a palindrome (616616).

The spelling of 1216615400 in words is "one billion, two hundred sixteen million, six hundred fifteen thousand, four hundred".