671998656 has 168 divisors, whose sum is σ = 2114190336. Its totient is φ = 184343040.

The previous prime is 671998609. The next prime is 671998693. The reversal of 671998656 is 656899176.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (168).

It is a junction number, because it is equal to n+sod(n) for n = 671998596 and 671998605.

It is a congruent number.

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 23 ways as a sum of consecutive naturals, for example, 5291265 + ... + 5291391.

Almost surely, 2^671998656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 671998656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1057095168).

671998656 is an abundant number, since it is smaller than the sum of its proper divisors (1442191680).

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

671998656 is a wasteful number, since it uses less digits than its factorization.

671998656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 307 (or 170 counting only the distinct ones).

The product of its digits is 4898880, while the sum is 57.

The square root of 671998656 is about 25922.9368706557. The cubic root of 671998656 is about 875.9032440413.

It can be divided in two parts, 67199 and 8656, that added together give a triangular number (75855 = T₃₈₉).

The spelling of 671998656 in words is "six hundred seventy-one million, nine hundred ninety-eight thousand, six hundred fifty-six".