21585816071 has 2 divisors, whose sum is σ = 21585816072. Its totient is φ = 21585816070.

The previous prime is 21585816041. The next prime is 21585816137. The reversal of 21585816071 is 17061858512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21585816071 - 2²² = 21581621767 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21585816041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10792908035 + 10792908036.

It is an arithmetic number, because the mean of its divisors is an integer number (10792908036).

Almost surely, 2^21585816071 is an apocalyptic number.

21585816071 is a deficient number, since it is larger than the sum of its proper divisors (1).

21585816071 is an equidigital number, since it uses as much as digits as its factorization.

21585816071 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 134400, while the sum is 44.

The spelling of 21585816071 in words is "twenty-one billion, five hundred eighty-five million, eight hundred sixteen thousand, seventy-one".