1221893639566 has 4 divisors (see below), whose sum is σ = 1832840459352. Its totient is φ = 610946819782.

The previous prime is 1221893639471. The next prime is 1221893639573. The reversal of 1221893639566 is 6659363981221.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 305473409890 + ... + 305473409893.

It is an arithmetic number, because the mean of its divisors is an integer number (458210114838).

Almost surely, 2^{1221893639566} is an apocalyptic number.

1221893639566 is a deficient number, since it is larger than the sum of its proper divisors (610946819786).

1221893639566 is an equidigital number, since it uses as much as digits as its factorization.

1221893639566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 610946819785.

The product of its digits is 25194240, while the sum is 61.

The spelling of 1221893639566 in words is "one trillion, two hundred twenty-one billion, eight hundred ninety-three million, six hundred thirty-nine thousand, five hundred sixty-six".