21131434405 has 4 divisors (see below), whose sum is σ = 25357721292. Its totient is φ = 16905147520.

The previous prime is 21131434393. The next prime is 21131434417. The reversal of 21131434405 is 50443413112.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21131434393) and next prime (21131434417).

It can be written as a sum of positive squares in 2 ways, for example, as 7207670404 + 13923764001 = 84898^2 + 117999^2 .

It is not a de Polignac number, because 21131434405 - 2⁹ = 21131433893 is a prime.

It is a Duffinian number.

It is a congruent 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, 2113143436 + ... + 2113143445.

It is an arithmetic number, because the mean of its divisors is an integer number (6339430323).

Almost surely, 2^21131434405 is an apocalyptic number.

It is an amenable number.

21131434405 is a deficient number, since it is larger than the sum of its proper divisors (4226286887).

21131434405 is an equidigital number, since it uses as much as digits as its factorization.

21131434405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4226286886.

The product of its (nonzero) digits is 5760, while the sum is 28.

Adding to 21131434405 its reverse (50443413112), we get a palindrome (71574847517).

The spelling of 21131434405 in words is "twenty-one billion, one hundred thirty-one million, four hundred thirty-four thousand, four hundred five".