665499999978 has 48 divisors (see below), whose sum is σ = 1573403416416. Its totient is φ = 201614946720.

The previous prime is 665499999977. The next prime is 665500000037. The reversal of 665499999978 is 879999994566.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (665499999977) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 346525 + ... + 1204607.

It is an arithmetic number, because the mean of its divisors is an integer number (32779237842).

Almost surely, 2^665499999978 is an apocalyptic number.

665499999978 is an abundant number, since it is smaller than the sum of its proper divisors (907903416438).

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

665499999978 is a wasteful number, since it uses less digits than its factorization.

665499999978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 862019 (or 862016 counting only the distinct ones).

The product of its digits is 21427701120, while the sum is 90.

The spelling of 665499999978 in words is "six hundred sixty-five billion, four hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred seventy-eight".