1216400091 has 16 divisors (see below), whose sum is σ = 1667520000. Its totient is φ = 788339168.

The previous prime is 1216400071. The next prime is 1216400093. The reversal of 1216400091 is 1900046121.

It is a cyclic number.

It is not a de Polignac number, because 1216400091 - 2¹⁹ = 1215875803 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1216400093) 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 15 ways as a sum of consecutive naturals, for example, 7941 + ... + 49958.

It is an arithmetic number, because the mean of its divisors is an integer number (104220000).

Almost surely, 2^1216400091 is an apocalyptic number.

1216400091 is a deficient number, since it is larger than the sum of its proper divisors (451119909).

1216400091 is a wasteful number, since it uses less digits than its factorization.

1216400091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58098.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 1216400091 is about 34876.9277746765. The cubic root of 1216400091 is about 1067.4777084380.

The spelling of 1216400091 in words is "one billion, two hundred sixteen million, four hundred thousand, ninety-one".