21434123309 has 2 divisors, whose sum is σ = 21434123310. Its totient is φ = 21434123308.

The previous prime is 21434123287. The next prime is 21434123357. The reversal of 21434123309 is 90332143412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14905968100 + 6528155209 = 122090^2 + 80797^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21434123309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21434122309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10717061654 + 10717061655.

It is an arithmetic number, because the mean of its divisors is an integer number (10717061655).

Almost surely, 2^21434123309 is an apocalyptic number.

It is an amenable number.

21434123309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21434123309 is an equidigital number, since it uses as much as digits as its factorization.

21434123309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 32.

The spelling of 21434123309 in words is "twenty-one billion, four hundred thirty-four million, one hundred twenty-three thousand, three hundred nine".