21310210121 has 2 divisors, whose sum is σ = 21310210122. Its totient is φ = 21310210120.

The previous prime is 21310210109. The next prime is 21310210139. The reversal of 21310210121 is 12101201312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17725194496 + 3585015625 = 133136^2 + 59875^2 .

It is a cyclic number.

It is not a de Polignac number, because 21310210121 - 2¹⁸ = 21309947977 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21310210096 and 21310210105.

It is not a weakly prime, because it can be changed into another prime (21310240121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655105060 + 10655105061.

It is an arithmetic number, because the mean of its divisors is an integer number (10655105061).

Almost surely, 2^21310210121 is an apocalyptic number.

It is an amenable number.

21310210121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21310210121 is an equidigital number, since it uses as much as digits as its factorization.

21310210121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21310210121 its reverse (12101201312), we get a palindrome (33411411433).

The spelling of 21310210121 in words is "twenty-one billion, three hundred ten million, two hundred ten thousand, one hundred twenty-one".