20505436505 has 8 divisors (see below), whose sum is σ = 24734019912. Its totient is φ = 16319351808.

The previous prime is 20505436487. The next prime is 20505436513. The reversal of 20505436505 is 50563450502.

It can be written as a sum of positive squares in 4 ways, for example, as 55696 + 20505380809 = 236^2 + 143197^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20505436505 - 2¹⁴ = 20505420121 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10623614 + ... + 10625543.

It is an arithmetic number, because the mean of its divisors is an integer number (3091752489).

Almost surely, 2^20505436505 is an apocalyptic number.

It is an amenable number.

20505436505 is a deficient number, since it is larger than the sum of its proper divisors (4228583407).

20505436505 is a wasteful number, since it uses less digits than its factorization.

20505436505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21249355.

The product of its (nonzero) digits is 90000, while the sum is 35.

The spelling of 20505436505 in words is "twenty billion, five hundred five million, four hundred thirty-six thousand, five hundred five".