821666053678 has 16 divisors (see below), whose sum is σ = 1243588432896. Its totient is φ = 407137642240.

The previous prime is 821666053669. The next prime is 821666053693. The reversal of 821666053678 is 876350666128.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1298850 + ... + 1824922.

It is an arithmetic number, because the mean of its divisors is an integer number (77724277056).

Almost surely, 2^821666053678 is an apocalyptic number.

821666053678 is a deficient number, since it is larger than the sum of its proper divisors (421922379218).

821666053678 is a wasteful number, since it uses less digits than its factorization.

821666053678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 533099.

The product of its (nonzero) digits is 17418240, while the sum is 58.

The spelling of 821666053678 in words is "eight hundred twenty-one billion, six hundred sixty-six million, fifty-three thousand, six hundred seventy-eight".