21000111210 has 48 divisors (see below), whose sum is σ = 58800314664. Its totient is φ = 5169257856.

The previous prime is 21000111179. The next prime is 21000111227. The reversal of 21000111210 is 1211100012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 11312236881 + 9687874329 = 106359^2 + 98427^2 .

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21000111192 and 21000111201.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8973237 + ... + 8975576.

Almost surely, 2^21000111210 is an apocalyptic number.

21000111210 is an abundant number, since it is smaller than the sum of its proper divisors (37800203454).

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

21000111210 is a wasteful number, since it uses less digits than its factorization.

21000111210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17948839 (or 17948836 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21000111210 its reverse (1211100012), we get a palindrome (22211211222).

The spelling of 21000111210 in words is "twenty-one billion, one hundred eleven thousand, two hundred ten".