1665915820 has 96 divisors (see below), whose sum is σ = 3841044480. Its totient is φ = 604558080.

The previous prime is 1665915809. The next prime is 1665915827. The reversal of 1665915820 is 285195661.

1665915820 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (1665915827) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1212654 + ... + 1214026.

It is an arithmetic number, because the mean of its divisors is an integer number (40010880).

Almost surely, 2^1665915820 is an apocalyptic number.

1665915820 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 1665915820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1920522240).

1665915820 is an abundant number, since it is smaller than the sum of its proper divisors (2175128660).

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

1665915820 is a wasteful number, since it uses less digits than its factorization.

1665915820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1535 (or 1533 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 43.

The square root of 1665915820 is about 40815.6320543980. The cubic root of 1665915820 is about 1185.4530293209.

The spelling of 1665915820 in words is "one billion, six hundred sixty-five million, nine hundred fifteen thousand, eight hundred twenty".