1216645527421 has 16 divisors (see below), whose sum is σ = 1326323756160. Its totient is φ = 1112493659200.

The previous prime is 1216645527407. The next prime is 1216645527431. The reversal of 1216645527421 is 1247255466121.

It is a cyclic number.

It is not a de Polignac number, because 1216645527421 - 2³⁵ = 1182285789053 is a prime.

It is a super-2 number, since 2×1216645527421² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216645527431) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8962615 + ... + 9097348.

It is an arithmetic number, because the mean of its divisors is an integer number (82895234760).

Almost surely, 2^{1216645527421} is an apocalyptic number.

It is an amenable number.

1216645527421 is a deficient number, since it is larger than the sum of its proper divisors (109678228739).

1216645527421 is a wasteful number, since it uses less digits than its factorization.

1216645527421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18060116.

The product of its digits is 806400, while the sum is 46.

The spelling of 1216645527421 in words is "one trillion, two hundred sixteen billion, six hundred forty-five million, five hundred twenty-seven thousand, four hundred twenty-one".