1665798920 has 64 divisors (see below), whose sum is σ = 3977424000. Its totient is φ = 626526208.

The previous prime is 1665798917. The next prime is 1665798923. The reversal of 1665798920 is 298975661.

It is an interprime number because it is at equal distance from previous prime (1665798917) and next prime (1665798923).

It is not an unprimeable number, because it can be changed into a prime (1665798923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38936 + ... + 69624.

It is an arithmetic number, because the mean of its divisors is an integer number (62147250).

Almost surely, 2^1665798920 is an apocalyptic number.

1665798920 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 1665798920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1988712000).

1665798920 is an abundant number, since it is smaller than the sum of its proper divisors (2311625080).

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

1665798920 is a wasteful number, since it uses less digits than its factorization.

1665798920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30782 (or 30778 counting only the distinct ones).

The product of its (nonzero) digits is 1632960, while the sum is 53.

The square root of 1665798920 is about 40814.1999799090. The cubic root of 1665798920 is about 1185.4253002886.

The spelling of 1665798920 in words is "one billion, six hundred sixty-five million, seven hundred ninety-eight thousand, nine hundred twenty".