21002120010 has 48 divisors (see below), whose sum is σ = 54655010280. Its totient is φ = 5595488640.

The previous prime is 21002119987. The next prime is 21002120081. The reversal of 21002120010 is 1002120012.

It can be written as a sum of positive squares in 4 ways, for example, as 14400720009 + 6601400001 = 120003^2 + 81249^2 .

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

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21002119974 and 21002120001.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5401 + ... + 205020.

Almost surely, 2^21002120010 is an apocalyptic number.

21002120010 is an abundant number, since it is smaller than the sum of its proper divisors (33652890270).

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

21002120010 is a wasteful number, since it uses less digits than its factorization.

21002120010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211543 (or 211540 counting only the distinct ones).

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

Adding to 21002120010 its reverse (1002120012), we get a palindrome (22004240022).

The spelling of 21002120010 in words is "twenty-one billion, two million, one hundred twenty thousand, ten".