121217211808 has 384 divisors, whose sum is σ = 321889075200. Its totient is φ = 43495833600.

The previous prime is 121217211803. The next prime is 121217211833. The reversal of 121217211808 is 808112712121.

It is a super-2 number, since 2×121217211808² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is not an unprimeable number, because it can be changed into a prime (121217211803) by changing a digit.

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 63 ways as a sum of consecutive naturals, for example, 634644993 + ... + 634645183.

It is an arithmetic number, because the mean of its divisors is an integer number (838252800).

Almost surely, 2^121217211808 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 121217211808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (160944537600).

121217211808 is an abundant number, since it is smaller than the sum of its proper divisors (200671863392).

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

121217211808 is a wasteful number, since it uses less digits than its factorization.

121217211808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 484 (or 476 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 34.

Adding to 121217211808 its reverse (808112712121), we get a palindrome (929329923929).

The spelling of 121217211808 in words is "one hundred twenty-one billion, two hundred seventeen million, two hundred eleven thousand, eight hundred eight".