1221538067620 has 96 divisors (see below), whose sum is σ = 2787034467168. Its totient is φ = 447043080192.

The previous prime is 1221538067611. The next prime is 1221538067639. The reversal of 1221538067620 is 267608351221.

It can be written as a sum of positive squares in 16 ways, for example, as 611489592484 + 610048475136 = 781978^2 + 781056^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 23233602 + ... + 23286118.

It is an arithmetic number, because the mean of its divisors is an integer number (29031609033).

Almost surely, 2^{1221538067620} is an apocalyptic number.

1221538067620 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 1221538067620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1393517233584).

1221538067620 is an abundant number, since it is smaller than the sum of its proper divisors (1565496399548).

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

1221538067620 is a wasteful number, since it uses less digits than its factorization.

1221538067620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53329 (or 53327 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 43.

The spelling of 1221538067620 in words is "one trillion, two hundred twenty-one billion, five hundred thirty-eight million, sixty-seven thousand, six hundred twenty".