21125621129 has 2 divisors, whose sum is σ = 21125621130. Its totient is φ = 21125621128.

The previous prime is 21125621113. The next prime is 21125621137. The reversal of 21125621129 is 92112652112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18836190025 + 2289431104 = 137245^2 + 47848^2 .

It is a cyclic number.

It is not a de Polignac number, because 21125621129 - 2⁴ = 21125621113 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21125621095 and 21125621104.

It is not a weakly prime, because it can be changed into another prime (21125621189) by changing a digit.

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 as a sum of consecutive naturals, namely, 10562810564 + 10562810565.

It is an arithmetic number, because the mean of its divisors is an integer number (10562810565).

Almost surely, 2^21125621129 is an apocalyptic number.

It is an amenable number.

21125621129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21125621129 is an equidigital number, since it uses as much as digits as its factorization.

21125621129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 32.

The spelling of 21125621129 in words is "twenty-one billion, one hundred twenty-five million, six hundred twenty-one thousand, one hundred twenty-nine".