21000012210 has 40 divisors (see below), whose sum is σ = 56466701676. Its totient is φ = 5600003040.

The previous prime is 21000012199. The next prime is 21000012217. The reversal of 21000012210 is 1221000012.

It can be written as a sum of positive squares in 2 ways, for example, as 19886922441 + 1113089769 = 141021^2 + 33363^2 .

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 = 21000012192 and 21000012201.

It is not an unprimeable number, because it can be changed into a prime (21000012217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 12962161 + ... + 12963780.

Almost surely, 2^21000012210 is an apocalyptic number.

21000012210 is an abundant number, since it is smaller than the sum of its proper divisors (35466689466).

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

21000012210 is a wasteful number, since it uses less digits than its factorization.

21000012210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25925960 (or 25925951 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21000012210 its reverse (1221000012), we get a palindrome (22221012222).

The spelling of 21000012210 in words is "twenty-one billion, twelve thousand, two hundred ten".