1221693950978 has 6 divisors (see below), whose sum is σ = 1832543271171. Its totient is φ = 610846193922.

The previous prime is 1221693950963. The next prime is 1221693951031. The reversal of 1221693950978 is 8790593961221.

It can be written as a sum of positive squares in only one way, i.e., 610846975489 + 610846975489 = 781567^2 + 781567^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=781567.

It is a super-2 number, since 2×1221693950978² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221693950978.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1172351 + ... + 1953917.

Almost surely, 2^{1221693950978} is an apocalyptic number.

1221693950978 is a deficient number, since it is larger than the sum of its proper divisors (610849320193).

1221693950978 is an frugal number, since it uses more digits than its factorization.

1221693950978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1563136 (or 781569 counting only the distinct ones).

The product of its (nonzero) digits is 14696640, while the sum is 62.

The spelling of 1221693950978 in words is "one trillion, two hundred twenty-one billion, six hundred ninety-three million, nine hundred fifty thousand, nine hundred seventy-eight".