21656060717 has 4 divisors (see below), whose sum is σ = 22159690080. Its totient is φ = 21152431356.

The previous prime is 21656060687. The next prime is 21656060731. The reversal of 21656060717 is 71706065612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21656060717 - 2¹⁰ = 21656059693 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 (21656060017) 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, 251814617 + ... + 251814702.

It is an arithmetic number, because the mean of its divisors is an integer number (5539922520).

Almost surely, 2^21656060717 is an apocalyptic number.

It is an amenable number.

21656060717 is a deficient number, since it is larger than the sum of its proper divisors (503629363).

21656060717 is an equidigital number, since it uses as much as digits as its factorization.

21656060717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503629362.

The product of its (nonzero) digits is 105840, while the sum is 41.

The spelling of 21656060717 in words is "twenty-one billion, six hundred fifty-six million, sixty thousand, seven hundred seventeen".