21304656717 has 16 divisors (see below), whose sum is σ = 30526080192. Its totient is φ = 13168108800.

The previous prime is 21304656689. The next prime is 21304656731. The reversal of 21304656717 is 71765640312.

It is a happy number.

It is not a de Polignac number, because 21304656717 - 2¹¹ = 21304654669 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21304656767) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3114034 + ... + 3120867.

It is an arithmetic number, because the mean of its divisors is an integer number (1907880012).

Almost surely, 2^21304656717 is an apocalyptic number.

It is an amenable number.

21304656717 is a deficient number, since it is larger than the sum of its proper divisors (9221423475).

21304656717 is a wasteful number, since it uses less digits than its factorization.

21304656717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6234988.

The product of its (nonzero) digits is 211680, while the sum is 42.

The spelling of 21304656717 in words is "twenty-one billion, three hundred four million, six hundred fifty-six thousand, seven hundred seventeen".