20949709717 has 4 divisors (see below), whose sum is σ = 21025340716. Its totient is φ = 20874078720.

The previous prime is 20949709709. The next prime is 20949709763. The reversal of 20949709717 is 71790794902.

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 8271174916 + 12678534801 = 90946^2 + 112599^2 .

It is a cyclic number.

It is not a de Polignac number, because 20949709717 - 2³ = 20949709709 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 (20949709777) 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 in 3 ways as a sum of consecutive naturals, for example, 37815084 + ... + 37815637.

It is an arithmetic number, because the mean of its divisors is an integer number (5256335179).

Almost surely, 2^20949709717 is an apocalyptic number.

It is an amenable number.

20949709717 is a deficient number, since it is larger than the sum of its proper divisors (75630999).

20949709717 is an equidigital number, since it uses as much as digits as its factorization.

20949709717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75630998.

The product of its (nonzero) digits is 2000376, while the sum is 55.

The spelling of 20949709717 in words is "twenty billion, nine hundred forty-nine million, seven hundred nine thousand, seven hundred seventeen".