1665236640 has 96 divisors (see below), whose sum is σ = 5266296000. Its totient is φ = 442302464.

The previous prime is 1665236611. The next prime is 1665236663. The reversal of 1665236640 is 466325661.

It is a tau number, because it is divible by the number of its divisors (96).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 116611 + ... + 130109.

It is an arithmetic number, because the mean of its divisors is an integer number (54857250).

Almost surely, 2^1665236640 is an apocalyptic number.

1665236640 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 1665236640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2633148000).

1665236640 is an abundant number, since it is smaller than the sum of its proper divisors (3601059360).

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

1665236640 is a wasteful number, since it uses less digits than its factorization.

1665236640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13774 (or 13766 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 39.

The square root of 1665236640 is about 40807.3111096529. The cubic root of 1665236640 is about 1185.2919076485.

The spelling of 1665236640 in words is "one billion, six hundred sixty-five million, two hundred thirty-six thousand, six hundred forty".