21655106687 has 2 divisors, whose sum is σ = 21655106688. Its totient is φ = 21655106686.

The previous prime is 21655106663. The next prime is 21655106701. The reversal of 21655106687 is 78660155612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21655106687 - 2¹⁶ = 21655041151 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21655106647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10827553343 + 10827553344.

It is an arithmetic number, because the mean of its divisors is an integer number (10827553344).

Almost surely, 2^21655106687 is an apocalyptic number.

21655106687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21655106687 is an equidigital number, since it uses as much as digits as its factorization.

21655106687 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 604800, while the sum is 47.

The spelling of 21655106687 in words is "twenty-one billion, six hundred fifty-five million, one hundred six thousand, six hundred eighty-seven".