21594695989 has 2 divisors, whose sum is σ = 21594695990. Its totient is φ = 21594695988.

The previous prime is 21594695987. The next prime is 21594696001. The reversal of 21594695989 is 98959649512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20102419089 + 1492276900 = 141783^2 + 38630^2 .

It is a cyclic number.

It is not a de Polignac number, because 21594695989 - 2¹ = 21594695987 is a prime.

Together with 21594695987, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21594695987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10797347994 + 10797347995.

It is an arithmetic number, because the mean of its divisors is an integer number (10797347995).

Almost surely, 2^21594695989 is an apocalyptic number.

It is an amenable number.

21594695989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21594695989 is an equidigital number, since it uses as much as digits as its factorization.

21594695989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62985600, while the sum is 67.

The spelling of 21594695989 in words is "twenty-one billion, five hundred ninety-four million, six hundred ninety-five thousand, nine hundred eighty-nine".