1666535820 has 48 divisors (see below), whose sum is σ = 4816831488. Its totient is φ = 430073280.

The previous prime is 1666535813. The next prime is 1666535831. The reversal of 1666535820 is 285356661.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 446134 + ... + 449853.

It is an arithmetic number, because the mean of its divisors is an integer number (100350656).

Almost surely, 2^1666535820 is an apocalyptic number.

1666535820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1666535820 is an abundant number, since it is smaller than the sum of its proper divisors (3150295668).

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

1666535820 is a wasteful number, since it uses less digits than its factorization.

1666535820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 896030 (or 896028 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 42.

The square root of 1666535820 is about 40823.2264770927. The cubic root of 1666535820 is about 1185.6000735092.

The spelling of 1666535820 in words is "one billion, six hundred sixty-six million, five hundred thirty-five thousand, eight hundred twenty".