21210120009931 has 2 divisors, whose sum is σ = 21210120009932. Its totient is φ = 21210120009930.

The previous prime is 21210120009929. The next prime is 21210120010081. The reversal of 21210120009931 is 13990002101212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21210120009931 - 2¹ = 21210120009929 is a prime.

It is a super-2 number, since 2×21210120009931² (a number of 27 digits) contains 22 as substring.

Together with 21210120009929, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21210120009893 and 21210120009902.

It is not a weakly prime, because it can be changed into another prime (21210120009901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605060004965 + 10605060004966.

It is an arithmetic number, because the mean of its divisors is an integer number (10605060004966).

Almost surely, 2^{21210120009931} is an apocalyptic number.

21210120009931 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210120009931 is an equidigital number, since it uses as much as digits as its factorization.

21210120009931 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 31.

The spelling of 21210120009931 in words is "twenty-one trillion, two hundred ten billion, one hundred twenty million, nine thousand, nine hundred thirty-one".