1221581921280 has 352 divisors, whose sum is σ = 4468352739840. Its totient is φ = 279029022720.

The previous prime is 1221581921267. The next prime is 1221581921297. The reversal of 1221581921280 is 821291851221.

It is a super-2 number, since 2×1221581921280² (a number of 25 digits) contains 22 as substring.

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

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 31 ways as a sum of consecutive naturals, for example, 212779210 + ... + 212784950.

It is an arithmetic number, because the mean of its divisors is an integer number (12694183920).

Almost surely, 2^{1221581921280} is an apocalyptic number.

1221581921280 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 1221581921280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2234176369920).

1221581921280 is an abundant number, since it is smaller than the sum of its proper divisors (3246770818560).

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

1221581921280 is a wasteful number, since it uses less digits than its factorization.

1221581921280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7755 (or 7737 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 42.

The spelling of 1221581921280 in words is "one trillion, two hundred twenty-one billion, five hundred eighty-one million, nine hundred twenty-one thousand, two hundred eighty".