1666535400 has 144 divisors (see below), whose sum is σ = 5716152000. Its totient is φ = 434931840.

The previous prime is 1666535371. The next prime is 1666535401. The reversal of 1666535400 is 45356661.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (1666535401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 74751 + ... + 94449.

It is an arithmetic number, because the mean of its divisors is an integer number (39695500).

Almost surely, 2^1666535400 is an apocalyptic number.

1666535400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1666535400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2858076000).

1666535400 is an abundant number, since it is smaller than the sum of its proper divisors (4049616600).

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

1666535400 is a wasteful number, since it uses less digits than its factorization.

1666535400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19768 (or 19756 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 36.

The square root of 1666535400 is about 40823.2213329620. The cubic root of 1666535400 is about 1185.5999739110.

The spelling of 1666535400 in words is "one billion, six hundred sixty-six million, five hundred thirty-five thousand, four hundred".