1216166400 has 720 divisors, whose sum is σ = 4986805824. Its totient is φ = 291962880.

The previous prime is 1216166389. The next prime is 1216166401. The reversal of 1216166400 is 46616121.

1216166400 is a `hidden beast` number, since 1 + 2 + 1 + 6 + 16 + 640 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

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

It is not an unprimeable number, because it can be changed into a prime (1216166401) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 52876789 + ... + 52876811.

Almost surely, 2^1216166400 is an apocalyptic number.

1216166400 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 1216166400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2493402912).

1216166400 is an abundant number, since it is smaller than the sum of its proper divisors (3770639424).

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

1216166400 is an equidigital number, since it uses as much as digits as its factorization.

1216166400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83 (or 50 counting only the distinct ones).

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

The square root of 1216166400 is about 34873.5773903395. The cubic root of 1216166400 is about 1067.4093438947.

The spelling of 1216166400 in words is "one billion, two hundred sixteen million, one hundred sixty-six thousand, four hundred".