1221755216620 has 24 divisors (see below), whose sum is σ = 2635028820144. Its totient is φ = 475493921856.

The previous prime is 1221755216611. The next prime is 1221755216639. The reversal of 1221755216620 is 266125571221.

It is a happy 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 7 ways as a sum of consecutive naturals, for example, 825509542 + ... + 825511021.

It is an arithmetic number, because the mean of its divisors is an integer number (109792867506).

Almost surely, 2^{1221755216620} is an apocalyptic number.

1221755216620 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221755216620 is an abundant number, since it is smaller than the sum of its proper divisors (1413273603524).

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

1221755216620 is a wasteful number, since it uses less digits than its factorization.

1221755216620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1651020609 (or 1651020607 counting only the distinct ones).

The product of its (nonzero) digits is 100800, while the sum is 40.

The spelling of 1221755216620 in words is "one trillion, two hundred twenty-one billion, seven hundred fifty-five million, two hundred sixteen thousand, six hundred twenty".