21695862641 has 2 divisors, whose sum is σ = 21695862642. Its totient is φ = 21695862640.

The previous prime is 21695862637. The next prime is 21695862649. The reversal of 21695862641 is 14626859612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21409542400 + 286320241 = 146320^2 + 16921^2 .

It is a cyclic number.

It is not a de Polignac number, because 21695862641 - 2² = 21695862637 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21695862641.

It is not a weakly prime, because it can be changed into another prime (21695862649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10847931320 + 10847931321.

It is an arithmetic number, because the mean of its divisors is an integer number (10847931321).

Almost surely, 2^21695862641 is an apocalyptic number.

It is an amenable number.

21695862641 is a deficient number, since it is larger than the sum of its proper divisors (1).

21695862641 is an equidigital number, since it uses as much as digits as its factorization.

21695862641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1244160, while the sum is 50.

The spelling of 21695862641 in words is "twenty-one billion, six hundred ninety-five million, eight hundred sixty-two thousand, six hundred forty-one".