21742364817 has 20 divisors (see below), whose sum is σ = 33527059456. Its totient is φ = 14027330520.

The previous prime is 21742364801. The next prime is 21742364857. The reversal of 21742364817 is 71846324712.

21742364817 is a `hidden beast` number, since 217 + 423 + 6 + 4 + 8 + 1 + 7 = 666.

It is not a de Polignac number, because 21742364817 - 2⁴ = 21742364801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21742364857) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 4326913 + ... + 4331934.

Almost surely, 2^21742364817 is an apocalyptic number.

21742364817 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21742364817 is a deficient number, since it is larger than the sum of its proper divisors (11784694639).

21742364817 is an equidigital number, since it uses as much as digits as its factorization.

21742364817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8658890 (or 8658881 counting only the distinct ones).

The product of its digits is 451584, while the sum is 45.

The spelling of 21742364817 in words is "twenty-one billion, seven hundred forty-two million, three hundred sixty-four thousand, eight hundred seventeen".