1665637440 has 224 divisors, whose sum is σ = 5524829184. Its totient is φ = 424673280.

The previous prime is 1665637429. The next prime is 1665637453. The reversal of 1665637440 is 447365661.

It is a junction number, because it is equal to n+sod(n) for n = 1665637392 and 1665637401.

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 31 ways as a sum of consecutive naturals, for example, 2886432 + ... + 2887008.

It is an arithmetic number, because the mean of its divisors is an integer number (24664416).

Almost surely, 2^1665637440 is an apocalyptic number.

1665637440 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 1665637440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2762414592).

1665637440 is an abundant number, since it is smaller than the sum of its proper divisors (3859191744).

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

1665637440 is a wasteful number, since it uses less digits than its factorization.

1665637440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 725 (or 715 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 42.

The square root of 1665637440 is about 40812.2216988980. The cubic root of 1665637440 is about 1185.3869946122.

The spelling of 1665637440 in words is "one billion, six hundred sixty-five million, six hundred thirty-seven thousand, four hundred forty".