1216805434221 has 32 divisors (see below), whose sum is σ = 1777003643520. Its totient is φ = 736036303104.

The previous prime is 1216805434213. The next prime is 1216805434223. The reversal of 1216805434221 is 1224345086121.

It is not a de Polignac number, because 1216805434221 - 2³ = 1216805434213 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1216805434221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216805434223) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 29333131 + ... + 29374583.

It is an arithmetic number, because the mean of its divisors is an integer number (55531363860).

Almost surely, 2^{1216805434221} is an apocalyptic number.

It is an amenable number.

1216805434221 is a deficient number, since it is larger than the sum of its proper divisors (560198209299).

1216805434221 is a wasteful number, since it uses less digits than its factorization.

1216805434221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54285.

The product of its (nonzero) digits is 92160, while the sum is 39.

The spelling of 1216805434221 in words is "one trillion, two hundred sixteen billion, eight hundred five million, four hundred thirty-four thousand, two hundred twenty-one".