21208460849 has 2 divisors, whose sum is σ = 21208460850. Its totient is φ = 21208460848.

The previous prime is 21208460831. The next prime is 21208460879. The reversal of 21208460849 is 94806480212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12049013824 + 9159447025 = 109768^2 + 95705^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21208460849 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21208460879) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10604230424 + 10604230425.

It is an arithmetic number, because the mean of its divisors is an integer number (10604230425).

Almost surely, 2^21208460849 is an apocalyptic number.

It is an amenable number.

21208460849 is a deficient number, since it is larger than the sum of its proper divisors (1).

21208460849 is an equidigital number, since it uses as much as digits as its factorization.

21208460849 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 221184, while the sum is 44.

The spelling of 21208460849 in words is "twenty-one billion, two hundred eight million, four hundred sixty thousand, eight hundred forty-nine".