1666213920 has 288 divisors, whose sum is σ = 6638381568. Its totient is φ = 372639744.

The previous prime is 1666213919. The next prime is 1666213921. The reversal of 1666213920 is 293126661.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1666213919) and next prime (1666213921).

It is a tau number, because it is divible by the number of its divisors (288).

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 (1666213921) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 472002 + ... + 475518.

It is an arithmetic number, because the mean of its divisors is an integer number (23049936).

Almost surely, 2^1666213920 is an apocalyptic number.

1666213920 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 1666213920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3319190784).

1666213920 is an abundant number, since it is smaller than the sum of its proper divisors (4972167648).

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

1666213920 is a wasteful number, since it uses less digits than its factorization.

1666213920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3592 (or 3581 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 1666213920 is about 40819.2836781833. The cubic root of 1666213920 is about 1185.5237336682.

The spelling of 1666213920 in words is "one billion, six hundred sixty-six million, two hundred thirteen thousand, nine hundred twenty".