1001000021 has 8 divisors (see below), whose sum is σ = 1152231360. Its totient is φ = 851826528.

The previous prime is 1000999949. The next prime is 1001000027. The reversal of 1001000021 is 1200001001.

It is a happy number.

1001000021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-1001000021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1000999969 and 1001000014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001000027) 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, 513416 + ... + 515361.

It is an arithmetic number, because the mean of its divisors is an integer number (144028920).

Almost surely, 2^1001000021 is an apocalyptic number.

It is an amenable number.

1001000021 is a deficient number, since it is larger than the sum of its proper divisors (151231339).

1001000021 is a wasteful number, since it uses less digits than its factorization.

1001000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1028923.

The product of its (nonzero) digits is 2, while the sum is 5.

The square root of 1001000021 is about 31638.5843709860. The cubic root of 1001000021 is about 1000.3332292792. Note that the first 3 decimals are identical.

Adding to 1001000021 its reverse (1200001001), we get a palindrome (2201001022).

The spelling of 1001000021 in words is "one billion, one million, twenty-one", and thus it is an aban number and an uban number.