20891105 has 4 divisors (see below), whose sum is σ = 25069332. Its totient is φ = 16712880.

The previous prime is 20891093. The next prime is 20891131. The reversal of 20891105 is 50119802.

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: 50119802 = 2 ⋅25059901.

It can be written as a sum of positive squares in 2 ways, for example, as 8620096 + 12271009 = 2936^2 + 3503^2 .

It is not a de Polignac number, because 20891105 - 2⁶ = 20891041 is a prime.

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, 2089106 + ... + 2089115.

It is an arithmetic number, because the mean of its divisors is an integer number (6267333).

Almost surely, 2^20891105 is an apocalyptic number.

It is an amenable number.

20891105 is a deficient number, since it is larger than the sum of its proper divisors (4178227).

20891105 is an equidigital number, since it uses as much as digits as its factorization.

20891105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4178226.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 20891105 is about 4570.6788336089. The cubic root of 20891105 is about 275.4147131214.

The spelling of 20891105 in words is "twenty million, eight hundred ninety-one thousand, one hundred five".