20847639413 has 2 divisors, whose sum is σ = 20847639414. Its totient is φ = 20847639412.

The previous prime is 20847639353. The next prime is 20847639431. The reversal of 20847639413 is 31493674802.

Together with next prime (20847639431) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14788262449 + 6059376964 = 121607^2 + 77842^2 .

It is a cyclic number.

It is not a de Polignac number, because 20847639413 - 2¹² = 20847635317 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20847639443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10423819706 + 10423819707.

It is an arithmetic number, because the mean of its divisors is an integer number (10423819707).

Almost surely, 2^20847639413 is an apocalyptic number.

It is an amenable number.

20847639413 is a deficient number, since it is larger than the sum of its proper divisors (1).

20847639413 is an equidigital number, since it uses as much as digits as its factorization.

20847639413 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 870912, while the sum is 47.

The spelling of 20847639413 in words is "twenty billion, eight hundred forty-seven million, six hundred thirty-nine thousand, four hundred thirteen".