19506439681 has 4 divisors (see below), whose sum is σ = 19569161664. Its totient is φ = 19443717700.

The previous prime is 19506439669. The next prime is 19506439691. The reversal of 19506439681 is 18693460591.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18693460591 = 13 ⋅1437958507.

It is a cyclic number.

It is not a de Polignac number, because 19506439681 - 2¹³ = 19506431489 is a prime.

It is a super-2 number, since 2×19506439681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19506439691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31360525 + ... + 31361146.

It is an arithmetic number, because the mean of its divisors is an integer number (4892290416).

Almost surely, 2^19506439681 is an apocalyptic number.

It is an amenable number.

19506439681 is a deficient number, since it is larger than the sum of its proper divisors (62721983).

19506439681 is an equidigital number, since it uses as much as digits as its factorization.

19506439681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62721982.

The product of its (nonzero) digits is 1399680, while the sum is 52.

The spelling of 19506439681 in words is "nineteen billion, five hundred six million, four hundred thirty-nine thousand, six hundred eighty-one".