21347238709 has 2 divisors, whose sum is σ = 21347238710. Its totient is φ = 21347238708.

The previous prime is 21347238667. The next prime is 21347238727. The reversal of 21347238709 is 90783274312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10877447025 + 10469791684 = 104295^2 + 102322^2 .

It is a cyclic number.

It is not a de Polignac number, because 21347238709 - 2¹⁷ = 21347107637 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21347238769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10673619354 + 10673619355.

It is an arithmetic number, because the mean of its divisors is an integer number (10673619355).

Almost surely, 2^21347238709 is an apocalyptic number.

It is an amenable number.

21347238709 is a deficient number, since it is larger than the sum of its proper divisors (1).

21347238709 is an equidigital number, since it uses as much as digits as its factorization.

21347238709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 508032, while the sum is 46.

The spelling of 21347238709 in words is "twenty-one billion, three hundred forty-seven million, two hundred thirty-eight thousand, seven hundred nine".