1221918587400 has 384 divisors, whose sum is σ = 4592848896000. Its totient is φ = 262510295040.

The previous prime is 1221918587333. The next prime is 1221918587401. The reversal of 1221918587400 is 47858191221.

It is a happy number.

It is a super-2 number, since 2×1221918587400² (a number of 25 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1221918587400.

It is not an unprimeable number, because it can be changed into a prime (1221918587401) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 10074316 + ... + 10194884.

It is an arithmetic number, because the mean of its divisors is an integer number (11960544000).

Almost surely, 2^{1221918587400} is an apocalyptic number.

1221918587400 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 1221918587400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2296424448000).

1221918587400 is an abundant number, since it is smaller than the sum of its proper divisors (3370930308600).

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

1221918587400 is a wasteful number, since it uses less digits than its factorization.

1221918587400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120741 (or 120732 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 48.

The spelling of 1221918587400 in words is "one trillion, two hundred twenty-one billion, nine hundred eighteen million, five hundred eighty-seven thousand, four hundred".