21717353792687 has 4 divisors (see below), whose sum is σ = 24819832905936. Its totient is φ = 18614874679440.

The previous prime is 21717353792671. The next prime is 21717353792699. The reversal of 21717353792687 is 78629735371712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21717353792687 - 2⁴ = 21717353792671 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21717353792627) 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, 1551239556614 + ... + 1551239556627.

It is an arithmetic number, because the mean of its divisors is an integer number (6204958226484).

Almost surely, 2^{21717353792687} is an apocalyptic number.

21717353792687 is a deficient number, since it is larger than the sum of its proper divisors (3102479113249).

21717353792687 is an equidigital number, since it uses as much as digits as its factorization.

21717353792687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3102479113248.

The product of its digits is 186701760, while the sum is 68.

The spelling of 21717353792687 in words is "twenty-one trillion, seven hundred seventeen billion, three hundred fifty-three million, seven hundred ninety-two thousand, six hundred eighty-seven".