1211997218544 has 800 divisors, whose sum is σ = 4474920193920. Its totient is φ = 308679081984.

The previous prime is 1211997218513. The next prime is 1211997218557. The reversal of 1211997218544 is 4458127991121.

1211997218544 is a `hidden beast` number, since 1 + 2 + 1 + 1 + 9 + 97 + 2 + 1 + 8 + 544 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 237039732 + ... + 237044844.

Almost surely, 2^{1211997218544} is an apocalyptic number.

1211997218544 is a gapful number since it is divisible by the number (14) 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 1211997218544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2237460096960).

1211997218544 is an abundant number, since it is smaller than the sum of its proper divisors (3262922975376).

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

1211997218544 is a wasteful number, since it uses less digits than its factorization.

1211997218544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5239 (or 5224 counting only the distinct ones).

The product of its digits is 1451520, while the sum is 54.

The spelling of 1211997218544 in words is "one trillion, two hundred eleven billion, nine hundred ninety-seven million, two hundred eighteen thousand, five hundred forty-four".