671821000 has 96 divisors (see below), whose sum is σ = 1660047480. Its totient is φ = 254448000.

The previous prime is 671820979. The next prime is 671821001. The reversal of 671821000 is 128176.

It can be written as a sum of positive squares in 4 ways, for example, as 25542916 + 646278084 = 5054^2 + 25422^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (671821001) by changing a digit.

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, 360070 + ... + 361930.

Almost surely, 2^671821000 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 671821000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (830023740).

671821000 is an abundant number, since it is smaller than the sum of its proper divisors (988226480).

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

671821000 is a wasteful number, since it uses less digits than its factorization.

671821000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1920 (or 1887 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 671821000 is about 25919.5100262331. The cubic root of 671821000 is about 875.8260498485.

Adding to 671821000 its reverse (128176), we get a palindrome (671949176).

The spelling of 671821000 in words is "six hundred seventy-one million, eight hundred twenty-one thousand".