21655610287 has 2 divisors, whose sum is σ = 21655610288. Its totient is φ = 21655610286.

The previous prime is 21655610281. The next prime is 21655610303. The reversal of 21655610287 is 78201655612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21655610287 - 2⁷ = 21655610159 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21655610281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10827805143 + 10827805144.

It is an arithmetic number, because the mean of its divisors is an integer number (10827805144).

Almost surely, 2^21655610287 is an apocalyptic number.

21655610287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21655610287 is an equidigital number, since it uses as much as digits as its factorization.

21655610287 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 201600, while the sum is 43.

The spelling of 21655610287 in words is "twenty-one billion, six hundred fifty-five million, six hundred ten thousand, two hundred eighty-seven".