1221779276720 has 80 divisors (see below), whose sum is σ = 2901414297600. Its totient is φ = 478257798912.

The previous prime is 1221779276687. The next prime is 1221779276743. The reversal of 1221779276720 is 276729771221.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49254881 + ... + 49279679.

It is an arithmetic number, because the mean of its divisors is an integer number (36267678720).

Almost surely, 2^{1221779276720} is an apocalyptic number.

1221779276720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221779276720 is an abundant number, since it is smaller than the sum of its proper divisors (1679635020880).

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

1221779276720 is a wasteful number, since it uses less digits than its factorization.

1221779276720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37962 (or 37956 counting only the distinct ones).

The product of its (nonzero) digits is 2074464, while the sum is 53.

The spelling of 1221779276720 in words is "one trillion, two hundred twenty-one billion, seven hundred seventy-nine million, two hundred seventy-six thousand, seven hundred twenty".