20684209213 has 4 divisors (see below), whose sum is σ = 21900927420. Its totient is φ = 19467491008.

The previous prime is 20684209193. The next prime is 20684209241. The reversal of 20684209213 is 31290248602.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31290248602 = 2 ⋅15645124301.

It can be written as a sum of positive squares in 2 ways, for example, as 10611678169 + 10072531044 = 103013^2 + 100362^2 .

It is a cyclic number.

It is not a de Polignac number, because 20684209213 - 2¹⁷ = 20684078141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20684209613) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 608359078 + ... + 608359111.

It is an arithmetic number, because the mean of its divisors is an integer number (5475231855).

Almost surely, 2^20684209213 is an apocalyptic number.

It is an amenable number.

20684209213 is a deficient number, since it is larger than the sum of its proper divisors (1216718207).

20684209213 is a wasteful number, since it uses less digits than its factorization.

20684209213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1216718206.

The product of its (nonzero) digits is 41472, while the sum is 37.

The spelling of 20684209213 in words is "twenty billion, six hundred eighty-four million, two hundred nine thousand, two hundred thirteen".