1666821366 has 24 divisors (see below), whose sum is σ = 4127367504. Its totient is φ = 476234640.

The previous prime is 1666821319. The next prime is 1666821383. The reversal of 1666821366 is 6631286661.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6614245 + ... + 6614496.

It is an arithmetic number, because the mean of its divisors is an integer number (171973646).

Almost surely, 2^1666821366 is an apocalyptic number.

1666821366 is an abundant number, since it is smaller than the sum of its proper divisors (2460546138).

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

1666821366 is a wasteful number, since it uses less digits than its factorization.

1666821366 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13228756 (or 13228753 counting only the distinct ones).

The product of its digits is 373248, while the sum is 45.

The square root of 1666821366 is about 40826.7236745737. The cubic root of 1666821366 is about 1185.6677836300.

The spelling of 1666821366 in words is "one billion, six hundred sixty-six million, eight hundred twenty-one thousand, three hundred sixty-six".