1216665816860 has 96 divisors (see below), whose sum is σ = 2799256169472. Its totient is φ = 441453265920.

The previous prime is 1216665816719. The next prime is 1216665816869. The reversal of 1216665816860 is 686185666121.

It is a super-2 number, since 2×1216665816860² (a number of 25 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (56) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 1216665816796 and 1216665816805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216665816869) 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, 17204534 + ... + 17275106.

It is an arithmetic number, because the mean of its divisors is an integer number (29158918432).

Almost surely, 2^{1216665816860} is an apocalyptic number.

1216665816860 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 1216665816860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1399628084736).

1216665816860 is an abundant number, since it is smaller than the sum of its proper divisors (1582590352612).

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

1216665816860 is a wasteful number, since it uses less digits than its factorization.

1216665816860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71743 (or 71741 counting only the distinct ones).

The product of its (nonzero) digits is 4976640, while the sum is 56.

The spelling of 1216665816860 in words is "one trillion, two hundred sixteen billion, six hundred sixty-five million, eight hundred sixteen thousand, eight hundred sixty".