1665515880 has 288 divisors, whose sum is σ = 6338217600. Its totient is φ = 378185472.

The previous prime is 1665515869. The next prime is 1665515909. The reversal of 1665515880 is 885155661.

1665515880 is a `hidden beast` number, since 1 + 6 + 65 + 5 + 1 + 588 + 0 = 666.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 4639141 + ... + 4639499.

It is an arithmetic number, because the mean of its divisors is an integer number (22007700).

Almost surely, 2^1665515880 is an apocalyptic number.

1665515880 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 1665515880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3169108800).

1665515880 is an abundant number, since it is smaller than the sum of its proper divisors (4672701720).

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

1665515880 is a wasteful number, since it uses less digits than its factorization.

1665515880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 653 (or 639 counting only the distinct ones).

The product of its (nonzero) digits is 288000, while the sum is 45.

The square root of 1665515880 is about 40810.7324119526. The cubic root of 1665515880 is about 1185.3581569742.

The spelling of 1665515880 in words is "one billion, six hundred sixty-five million, five hundred fifteen thousand, eight hundred eighty".