21395558929 has 2 divisors, whose sum is σ = 21395558930. Its totient is φ = 21395558928.

The previous prime is 21395558927. The next prime is 21395558959. The reversal of 21395558929 is 92985559312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18029238529 + 3366320400 = 134273^2 + 58020^2 .

It is a cyclic number.

It is not a de Polignac number, because 21395558929 - 2¹ = 21395558927 is a prime.

Together with 21395558927, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21395558927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10697779464 + 10697779465.

It is an arithmetic number, because the mean of its divisors is an integer number (10697779465).

Almost surely, 2^21395558929 is an apocalyptic number.

It is an amenable number.

21395558929 is a deficient number, since it is larger than the sum of its proper divisors (1).

21395558929 is an equidigital number, since it uses as much as digits as its factorization.

21395558929 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8748000, while the sum is 58.

The spelling of 21395558929 in words is "twenty-one billion, three hundred ninety-five million, five hundred fifty-eight thousand, nine hundred twenty-nine".