20916408517 has 4 divisors (see below), whose sum is σ = 20919028140. Its totient is φ = 20913788896.

The previous prime is 20916408509. The next prime is 20916408547. The reversal of 20916408517 is 71580461902.

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 9370046401 + 11546362116 = 96799^2 + 107454^2 .

It is a cyclic number.

It is not a de Polignac number, because 20916408517 - 2³ = 20916408509 is a prime.

It is a super-2 number, since 2×20916408517² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20916408547) 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, 1297798 + ... + 1313815.

It is an arithmetic number, because the mean of its divisors is an integer number (5229757035).

Almost surely, 2^20916408517 is an apocalyptic number.

It is an amenable number.

20916408517 is a deficient number, since it is larger than the sum of its proper divisors (2619623).

20916408517 is an equidigital number, since it uses as much as digits as its factorization.

20916408517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2619622.

The product of its (nonzero) digits is 120960, while the sum is 43.

The spelling of 20916408517 in words is "twenty billion, nine hundred sixteen million, four hundred eight thousand, five hundred seventeen".