21215249129 has 2 divisors, whose sum is σ = 21215249130. Its totient is φ = 21215249128.

The previous prime is 21215249051. The next prime is 21215249131. The reversal of 21215249129 is 92194251212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21126041104 + 89208025 = 145348^2 + 9445^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21215249129 is a prime.

Together with 21215249131, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21215249092 and 21215249101.

It is not a weakly prime, because it can be changed into another prime (21215249929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10607624564 + 10607624565.

It is an arithmetic number, because the mean of its divisors is an integer number (10607624565).

Almost surely, 2^21215249129 is an apocalyptic number.

It is an amenable number.

21215249129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21215249129 is an equidigital number, since it uses as much as digits as its factorization.

21215249129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 38.

The spelling of 21215249129 in words is "twenty-one billion, two hundred fifteen million, two hundred forty-nine thousand, one hundred twenty-nine".