1221212664672 has 384 divisors, whose sum is σ = 4335597923328. Its totient is φ = 290657894400.

The previous prime is 1221212664643. The next prime is 1221212664673. The reversal of 1221212664672 is 2764662121221.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221212664673) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 13118772 + ... + 13211532.

It is an arithmetic number, because the mean of its divisors is an integer number (11290619592).

Almost surely, 2^{1221212664672} is an apocalyptic number.

1221212664672 is a gapful number since it is divisible by the number (12) 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 1221212664672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2167798961664).

1221212664672 is an abundant number, since it is smaller than the sum of its proper divisors (3114385258656).

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

1221212664672 is a wasteful number, since it uses less digits than its factorization.

1221212664672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92942 (or 92934 counting only the distinct ones).

The product of its digits is 193536, while the sum is 42.

Adding to 1221212664672 its reverse (2764662121221), we get a palindrome (3985874785893).

The spelling of 1221212664672 in words is "one trillion, two hundred twenty-one billion, two hundred twelve million, six hundred sixty-four thousand, six hundred seventy-two".