1216409400 has 264 divisors, whose sum is σ = 4283390280. Its totient is φ = 321226560.

The previous prime is 1216409309. The next prime is 1216409401. The reversal of 1216409400 is 49046121.

1216409400 is a `hidden beast` number, since 1 + 216 + 40 + 9 + 400 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216409401) by changing a digit.

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 65 ways as a sum of consecutive naturals, for example, 11809749 + ... + 11809851.

Almost surely, 2^1216409400 is an apocalyptic number.

1216409400 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 1216409400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2141695140).

1216409400 is an abundant number, since it is smaller than the sum of its proper divisors (3066980880).

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

1216409400 is an equidigital number, since it uses as much as digits as its factorization.

1216409400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149 (or 113 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 1216409400 is about 34877.0612294098. The cubic root of 1216409400 is about 1067.4804315346.

The spelling of 1216409400 in words is "one billion, two hundred sixteen million, four hundred nine thousand, four hundred".