1665637540 has 24 divisors (see below), whose sum is σ = 3997530432. Its totient is φ = 571075680.

The previous prime is 1665637531. The next prime is 1665637541. The reversal of 1665637540 is 457365661.

It is not an unprimeable number, because it can be changed into a prime (1665637541) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5948566 + ... + 5948845.

It is an arithmetic number, because the mean of its divisors is an integer number (166563768).

Almost surely, 2^1665637540 is an apocalyptic number.

1665637540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1665637540 is an abundant number, since it is smaller than the sum of its proper divisors (2331892892).

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

1665637540 is a wasteful number, since it uses less digits than its factorization.

1665637540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11897427 (or 11897425 counting only the distinct ones).

The product of its (nonzero) digits is 453600, while the sum is 43.

The square root of 1665637540 is about 40812.2229240212. Note that the first 3 decimals coincide. The cubic root of 1665637540 is about 1185.3870183346.

The spelling of 1665637540 in words is "one billion, six hundred sixty-five million, six hundred thirty-seven thousand, five hundred forty".