665616420 has 96 divisors (see below), whose sum is σ = 2366649600. Its totient is φ = 152140032.

The previous prime is 665616359. The next prime is 665616461. The reversal of 665616420 is 24616566.

It is a happy number.

665616420 is a `hidden beast` number, since 6 + 6 + 5 + 6 + 1 + 642 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 84265 + ... + 91824.

It is an arithmetic number, because the mean of its divisors is an integer number (24652600).

Almost surely, 2^665616420 is an apocalyptic number.

665616420 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

665616420 is an abundant number, since it is smaller than the sum of its proper divisors (1701033180).

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

665616420 is a wasteful number, since it uses less digits than its factorization.

665616420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176114 (or 176106 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 665616420 is about 25799.5430192087. The cubic root of 665616420 is about 873.1214861459.

The spelling of 665616420 in words is "six hundred sixty-five million, six hundred sixteen thousand, four hundred twenty".