66440154640 has 40 divisors (see below), whose sum is σ = 154581724440. Its totient is φ = 26557418496.

The previous prime is 66440154637. The next prime is 66440154661. The reversal of 66440154640 is 4645104466.

It can be written as a sum of positive squares in 4 ways, for example, as 3595681296 + 62844473344 = 59964^2 + 250688^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×66440154640² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 66440154593 and 66440154602.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 176269 + ... + 404908.

It is an arithmetic number, because the mean of its divisors is an integer number (3864543111).

Almost surely, 2^66440154640 is an apocalyptic number.

It is an amenable number.

66440154640 is an abundant number, since it is smaller than the sum of its proper divisors (88141569800).

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

66440154640 is a wasteful number, since it uses less digits than its factorization.

66440154640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 582619 (or 582613 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 40.

The spelling of 66440154640 in words is "sixty-six billion, four hundred forty million, one hundred fifty-four thousand, six hundred forty".