21205743417 has 12 divisors (see below), whose sum is σ = 30659347264. Its totient is φ = 14123856600.

The previous prime is 21205743413. The next prime is 21205743431. The reversal of 21205743417 is 71434750212.

21205743417 is a `hidden beast` number, since 2 + 1 + 205 + 7 + 434 + 17 = 666.

It is not a de Polignac number, because 21205743417 - 2² = 21205743413 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21205743413) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1098709 + ... + 1117842.

Almost surely, 2^21205743417 is an apocalyptic number.

It is an amenable number.

21205743417 is a deficient number, since it is larger than the sum of its proper divisors (9453603847).

21205743417 is a wasteful number, since it uses less digits than its factorization.

21205743417 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2217620 (or 2217617 counting only the distinct ones).

The product of its (nonzero) digits is 47040, while the sum is 36.

The spelling of 21205743417 in words is "twenty-one billion, two hundred five million, seven hundred forty-three thousand, four hundred seventeen".