21679970689 has 4 divisors (see below), whose sum is σ = 23347660756.
Its totient is φ = 20012280624.
The previous prime is 21679970677. The next prime is 21679970699. The reversal of 21679970689 is 98607997612.
It is a semiprime because it is the product of two primes.
It can be written as a sum of positive squares in 2 ways, for example, as 13576910400 + 8103060289 = 116520^2 + 90017^2
It is a cyclic number.
It is not a de Polignac number, because 21679970689 - 213 = 21679962497 is a prime.
It is a super-2 number, since 2×216799706892 (a number of 21 digits) contains 22 as substring.
It is a Duffinian number.
It is a self number, because there is not a number n which added to its sum of digits gives 21679970689.
It is not an unprimeable number, because it can be changed into a prime (21679970699) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (13) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 833845014 + ... + 833845039.
It is an arithmetic number, because the mean of its divisors is an integer number (5836915189).
Almost surely, 221679970689 is an apocalyptic number.
It is an amenable number.
21679970689 is a deficient number, since it is larger than the sum of its proper divisors (1667690067).
21679970689 is a wasteful number, since it uses less digits than its factorization.
21679970689 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 1667690066.
The product of its (nonzero) digits is 20575296, while the sum is 64.
The spelling of 21679970689 in words is "twenty-one billion, six hundred seventy-nine million, nine hundred seventy thousand, six hundred eighty-nine".