1321666778 has 8 divisors (see below), whose sum is σ = 1984025568. Its totient is φ = 660324924.

The previous prime is 1321666763. The next prime is 1321666799. The reversal of 1321666778 is 8776661231.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 250976 + ... + 256187.

It is an arithmetic number, because the mean of its divisors is an integer number (248003196).

Almost surely, 2^1321666778 is an apocalyptic number.

1321666778 is a deficient number, since it is larger than the sum of its proper divisors (662358790).

1321666778 is a wasteful number, since it uses less digits than its factorization.

1321666778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 508468.

The product of its digits is 508032, while the sum is 47.

The square root of 1321666778 is about 36354.7352899179. The cubic root of 1321666778 is about 1097.4228311790.

The spelling of 1321666778 in words is "one billion, three hundred twenty-one million, six hundred sixty-six thousand, seven hundred seventy-eight".