100405391 has 4 divisors (see below), whose sum is σ = 100514400. Its totient is φ = 100296384.

The previous prime is 100405381. The next prime is 100405397. The reversal of 100405391 is 193504001.

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: 193504001 = 7883 ⋅24547.

It is a cyclic number.

It is not a de Polignac number, because 100405391 - 2¹⁸ = 100143247 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100405397) 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, 53111 + ... + 54968.

It is an arithmetic number, because the mean of its divisors is an integer number (25128600).

Almost surely, 2^100405391 is an apocalyptic number.

100405391 is a deficient number, since it is larger than the sum of its proper divisors (109009).

100405391 is an equidigital number, since it uses as much as digits as its factorization.

100405391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109008.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 100405391 is about 10020.2490488011. The cubic root of 100405391 is about 464.7852571475.

Adding to 100405391 its reverse (193504001), we get a palindrome (293909392).

The spelling of 100405391 in words is "one hundred million, four hundred five thousand, three hundred ninety-one".