1665823440 has 320 divisors, whose sum is σ = 5631639552. Its totient is φ = 406425600.

The previous prime is 1665823433. The next prime is 1665823447. The reversal of 1665823440 is 443285661.

It is an interprime number because it is at equal distance from previous prime (1665823433) and next prime (1665823447).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665823447) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 13116657 + ... + 13116783.

Almost surely, 2^1665823440 is an apocalyptic number.

1665823440 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 1665823440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2815819776).

1665823440 is an abundant number, since it is smaller than the sum of its proper divisors (3965816112).

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

1665823440 is a wasteful number, since it uses less digits than its factorization.

1665823440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258 (or 252 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 39.

The square root of 1665823440 is about 40814.5003644538. The cubic root of 1665823440 is about 1185.4311166141.

The spelling of 1665823440 in words is "one billion, six hundred sixty-five million, eight hundred twenty-three thousand, four hundred forty".