21010210121 has 12 divisors (see below), whose sum is σ = 22326008892. Its totient is φ = 19767932928.

The previous prime is 21010210097. The next prime is 21010210141. The reversal of 21010210121 is 12101201012.

It can be written as a sum of positive squares in 6 ways, for example, as 786241600 + 20223968521 = 28040^2 + 142211^2 .

It is not a de Polignac number, because 21010210121 - 2⁶ = 21010210057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21010210141) 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 11 ways as a sum of consecutive naturals, for example, 1051601 + ... + 1071393.

It is an arithmetic number, because the mean of its divisors is an integer number (1860500741).

Almost surely, 2^21010210121 is an apocalyptic number.

It is an amenable number.

21010210121 is a deficient number, since it is larger than the sum of its proper divisors (1315798771).

21010210121 is a wasteful number, since it uses less digits than its factorization.

21010210121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23500 (or 23483 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21010210121 its reverse (12101201012), we get a palindrome (33111411133).

The spelling of 21010210121 in words is "twenty-one billion, ten million, two hundred ten thousand, one hundred twenty-one".