21208421413 has 2 divisors, whose sum is σ = 21208421414. Its totient is φ = 21208421412.

The previous prime is 21208421407. The next prime is 21208421447. The reversal of 21208421413 is 31412480212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14708353284 + 6500068129 = 121278^2 + 80623^2 .

It is a cyclic number.

It is not a de Polignac number, because 21208421413 - 2¹³ = 21208413221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21208421473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10604210706 + 10604210707.

It is an arithmetic number, because the mean of its divisors is an integer number (10604210707).

Almost surely, 2^21208421413 is an apocalyptic number.

It is an amenable number.

21208421413 is a deficient number, since it is larger than the sum of its proper divisors (1).

21208421413 is an equidigital number, since it uses as much as digits as its factorization.

21208421413 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3072, while the sum is 28.

The spelling of 21208421413 in words is "twenty-one billion, two hundred eight million, four hundred twenty-one thousand, four hundred thirteen".