20845843505 has 4 divisors (see below), whose sum is σ = 25015012212. Its totient is φ = 16676674800.

The previous prime is 20845843433. The next prime is 20845843511. The reversal of 20845843505 is 50534854802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50534854802 = 2 ⋅25267427401.

It can be written as a sum of positive squares in 2 ways, for example, as 6099141409 + 14746702096 = 78097^2 + 121436^2 .

It is not a de Polignac number, because 20845843505 - 2²² = 20841649201 is a prime.

It is a super-3 number, since 3×20845843505³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2084584346 + ... + 2084584355.

It is an arithmetic number, because the mean of its divisors is an integer number (6253753053).

Almost surely, 2^20845843505 is an apocalyptic number.

It is an amenable number.

20845843505 is a deficient number, since it is larger than the sum of its proper divisors (4169168707).

20845843505 is an equidigital number, since it uses as much as digits as its factorization.

20845843505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4169168706.

The product of its (nonzero) digits is 768000, while the sum is 44.

The spelling of 20845843505 in words is "twenty billion, eight hundred forty-five million, eight hundred forty-three thousand, five hundred five".