21000022 has 8 divisors (see below), whose sum is σ = 31541400. Its totient is φ = 10486224.

The previous prime is 20999999. The next prime is 21000037. The reversal of 21000022 is 22000012.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 20999969 and 21000014.

It is a congruent number.

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, 4872 + ... + 8107.

It is an arithmetic number, because the mean of its divisors is an integer number (3942675).

Almost surely, 2^21000022 is an apocalyptic number.

21000022 is a deficient number, since it is larger than the sum of its proper divisors (10541378).

21000022 is a wasteful number, since it uses less digits than its factorization.

21000022 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13790.

The product of its (nonzero) digits is 8, while the sum is 7.

The square root of 21000022 is about 4582.5780953520. The cubic root of 21000022 is about 275.8925139815.

Adding to 21000022 its reverse (22000012), we get a palindrome (43000034).

The spelling of 21000022 in words is "twenty-one million, twenty-two", and thus it is an aban number and an uban number.