21000002 has 8 divisors (see below), whose sum is σ = 32586300. Its totient is φ = 10137904.

The previous prime is 20999999. The next prime is 21000037. The reversal of 21000002 is 20000012.

It can be written as a sum of positive squares in 2 ways, for example, as 20967241 + 32761 = 4579^2 + 181^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 21000002.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 180977 + ... + 181092.

Almost surely, 2^21000002 is an apocalyptic number.

21000002 is a deficient number, since it is larger than the sum of its proper divisors (11586298).

21000002 is a wasteful number, since it uses less digits than its factorization.

21000002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 362100.

The product of its (nonzero) digits is 4, while the sum is 5.

The square root of 21000002 is about 4582.5759131737. The cubic root of 21000002 is about 275.8924263966.

Adding to 21000002 its reverse (20000012), we get a palindrome (41000014).

Multiplying 21000002 by its reverse (20000012), we get a palindrome (420000292000024).

The spelling of 21000002 in words is "twenty-one million, two", and thus it is an aban number and an uban number.