19721591320647 has 8 divisors (see below), whose sum is σ = 26296012519920. Its totient is φ = 13147448834240.

The previous prime is 19721591320591. The next prime is 19721591320679. The reversal of 19721591320647 is 74602319512791.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19721591320647 - 2¹⁸ = 19721591058503 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19721591324647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69513054 + ... + 69796187.

It is an arithmetic number, because the mean of its divisors is an integer number (3287001564990).

Almost surely, 2^{19721591320647} is an apocalyptic number.

19721591320647 is a deficient number, since it is larger than the sum of its proper divisors (6574421199273).

19721591320647 is a wasteful number, since it uses less digits than its factorization.

19721591320647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139356433.

The product of its (nonzero) digits is 5715360, while the sum is 57.

The spelling of 19721591320647 in words is "nineteen trillion, seven hundred twenty-one billion, five hundred ninety-one million, three hundred twenty thousand, six hundred forty-seven".