665868816 has 40 divisors (see below), whose sum is σ = 1911291360. Its totient is φ = 221956128.

The previous prime is 665868799. The next prime is 665868817. The reversal of 665868816 is 618868566.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (665868817) 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, 770250 + ... + 771113.

It is an arithmetic number, because the mean of its divisors is an integer number (47782284).

Almost surely, 2^665868816 is an apocalyptic number.

It is an amenable number.

665868816 is an abundant number, since it is smaller than the sum of its proper divisors (1245422544).

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

665868816 is a wasteful number, since it uses less digits than its factorization.

665868816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1541380 (or 1541368 counting only the distinct ones).

The product of its digits is 3317760, while the sum is 54.

The square root of 665868816 is about 25804.4340375835. The cubic root of 665868816 is about 873.2318322429.

The spelling of 665868816 in words is "six hundred sixty-five million, eight hundred sixty-eight thousand, eight hundred sixteen".