100643905 has 4 divisors (see below), whose sum is σ = 120772692. Its totient is φ = 80515120.

The previous prime is 100643843. The next prime is 100643941. The reversal of 100643905 is 509346001.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 509346001 = 107 ⋅4760243.

It can be written as a sum of positive squares in 2 ways, for example, as 52881984 + 47761921 = 7272^2 + 6911^2 .

It is not a de Polignac number, because 100643905 - 2¹¹ = 100641857 is a prime.

It is a super-2 number, since 2×100643905² = 20258391227298050, which contains 22 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, 10064386 + ... + 10064395.

It is an arithmetic number, because the mean of its divisors is an integer number (30193173).

Almost surely, 2^100643905 is an apocalyptic number.

It is an amenable number.

100643905 is a deficient number, since it is larger than the sum of its proper divisors (20128787).

100643905 is an equidigital number, since it uses as much as digits as its factorization.

100643905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20128786.

The product of its (nonzero) digits is 3240, while the sum is 28.

The square root of 100643905 is about 10032.1435894828. The cubic root of 100643905 is about 465.1530001015.

Adding to 100643905 its reverse (509346001), we get a palindrome (609989906).

The spelling of 100643905 in words is "one hundred million, six hundred forty-three thousand, nine hundred five".