19965421447 has 4 divisors (see below), whose sum is σ = 20390217696. Its totient is φ = 19540625200.

The previous prime is 19965421417. The next prime is 19965421453. The reversal of 19965421447 is 74412456991.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74412456991 = 23 ⋅3235324217.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19965421447 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19965421394 and 19965421403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19965421417) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 212398054 + ... + 212398147.

It is an arithmetic number, because the mean of its divisors is an integer number (5097554424).

Almost surely, 2^19965421447 is an apocalyptic number.

19965421447 is a deficient number, since it is larger than the sum of its proper divisors (424796249).

19965421447 is an equidigital number, since it uses as much as digits as its factorization.

19965421447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 424796248.

The product of its digits is 2177280, while the sum is 52.

The spelling of 19965421447 in words is "nineteen billion, nine hundred sixty-five million, four hundred twenty-one thousand, four hundred forty-seven".