1665906457638 has 32 divisors (see below), whose sum is σ = 3377593276416. Its totient is φ = 547672719168.

The previous prime is 1665906457601. The next prime is 1665906457729. The reversal of 1665906457638 is 8367546095661.

It is a congruent number.

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, 13097295 + ... + 13223877.

It is an arithmetic number, because the mean of its divisors is an integer number (105549789888).

Almost surely, 2^{1665906457638} is an apocalyptic number.

1665906457638 is an abundant number, since it is smaller than the sum of its proper divisors (1711686818778).

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

1665906457638 is a wasteful number, since it uses less digits than its factorization.

1665906457638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156708.

The product of its (nonzero) digits is 195955200, while the sum is 66.

The spelling of 1665906457638 in words is "one trillion, six hundred sixty-five billion, nine hundred six million, four hundred fifty-seven thousand, six hundred thirty-eight".