1221551944704 has 792 divisors, whose sum is σ = 4595545131840. Its totient is φ = 305159602176.

The previous prime is 1221551944681. The next prime is 1221551944751. The reversal of 1221551944704 is 4074491551221.

It is a happy number.

1221551944704 is a `hidden beast` number, since 1 + 2 + 2 + 1 + 551 + 94 + 4 + 7 + 0 + 4 = 666.

It is a super-2 number, since 2×1221551944704² (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 1221551944704.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 207145084 + ... + 207150980.

Almost surely, 2^{1221551944704} is an apocalyptic number.

1221551944704 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 1221551944704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2297772565920).

1221551944704 is an abundant number, since it is smaller than the sum of its proper divisors (3373993187136).

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

1221551944704 is a wasteful number, since it uses less digits than its factorization.

1221551944704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5975 (or 5941 counting only the distinct ones).

The product of its (nonzero) digits is 403200, while the sum is 45.

The spelling of 1221551944704 in words is "one trillion, two hundred twenty-one billion, five hundred fifty-one million, nine hundred forty-four thousand, seven hundred four".