19805139547 has 2 divisors, whose sum is σ = 19805139548. Its totient is φ = 19805139546.

The previous prime is 19805139521. The next prime is 19805139583. The reversal of 19805139547 is 74593150891.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19805139547 - 2²⁷ = 19670921819 is a prime.

It is a super-2 number, since 2×19805139547² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 19805139494 and 19805139503.

It is not a weakly prime, because it can be changed into another prime (19805130547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9902569773 + 9902569774.

It is an arithmetic number, because the mean of its divisors is an integer number (9902569774).

Almost surely, 2^19805139547 is an apocalyptic number.

19805139547 is a deficient number, since it is larger than the sum of its proper divisors (1).

19805139547 is an equidigital number, since it uses as much as digits as its factorization.

19805139547 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1360800, while the sum is 52.

The spelling of 19805139547 in words is "nineteen billion, eight hundred five million, one hundred thirty-nine thousand, five hundred forty-seven".