1000643868 has 288 divisors, whose sum is σ = 3266984448. Its totient is φ = 261273600.

The previous prime is 1000643863. The next prime is 1000643881. The reversal of 1000643868 is 8683460001.

It is a happy number.

1000643868 is a `hidden beast` number, since 1 + 0 + 0 + 0 + 643 + 8 + 6 + 8 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1000643863) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4742283 + ... + 4742493.

It is an arithmetic number, because the mean of its divisors is an integer number (11343696).

Almost surely, 2^1000643868 is an apocalyptic number.

1000643868 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1000643868, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1633492224).

1000643868 is an abundant number, since it is smaller than the sum of its proper divisors (2266340580).

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

1000643868 is a wasteful number, since it uses less digits than its factorization.

1000643868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 295 (or 281 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The square root of 1000643868 is about 31632.9554104576. The cubic root of 1000643868 is about 1000.2145766202.

The spelling of 1000643868 in words is "one billion, six hundred forty-three thousand, eight hundred sixty-eight".