21002100210 has 288 divisors, whose sum is σ = 70262770032. Its totient is φ = 4311014400.

The previous prime is 21002100199. The next prime is 21002100221. The reversal of 21002100210 is 1200120012.

It is an interprime number because it is at equal distance from previous prime (21002100199) and next prime (21002100221).

It can be written as a sum of positive squares in 8 ways, for example, as 15596762769 + 5405337441 = 124887^2 + 73521^2 .

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

21002100210 is a modest number, since divided by 2100210 gives 210 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 21002100192 and 21002100201.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 2116260 + ... + 2126160.

Almost surely, 2^21002100210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21002100210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35131385016).

21002100210 is an abundant number, since it is smaller than the sum of its proper divisors (49260669822).

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

21002100210 is a wasteful number, since it uses less digits than its factorization.

21002100210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9978 (or 9968 counting only the distinct ones).

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

Adding to 21002100210 its reverse (1200120012), we get a palindrome (22202220222).

The spelling of 21002100210 in words is "twenty-one billion, two million, one hundred thousand, two hundred ten".