21651212029 has 2 divisors, whose sum is σ = 21651212030. Its totient is φ = 21651212028.

The previous prime is 21651212027. The next prime is 21651212047. The reversal of 21651212029 is 92021215612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13016528100 + 8634683929 = 114090^2 + 92923^2 .

It is a cyclic number.

It is not a de Polignac number, because 21651212029 - 2¹ = 21651212027 is a prime.

Together with 21651212027, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21651212027) 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 as a sum of consecutive naturals, namely, 10825606014 + 10825606015.

It is an arithmetic number, because the mean of its divisors is an integer number (10825606015).

Almost surely, 2^21651212029 is an apocalyptic number.

It is an amenable number.

21651212029 is a deficient number, since it is larger than the sum of its proper divisors (1).

21651212029 is an equidigital number, since it uses as much as digits as its factorization.

21651212029 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 31.

The spelling of 21651212029 in words is "twenty-one billion, six hundred fifty-one million, two hundred twelve thousand, twenty-nine".