21612051717 has 4 divisors (see below), whose sum is σ = 28816068960. Its totient is φ = 14408034476.

The previous prime is 21612051677. The next prime is 21612051743. The reversal of 21612051717 is 71715021612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21612051717 - 2²² = 21607857413 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21612051917) 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, 3602008617 + ... + 3602008622.

It is an arithmetic number, because the mean of its divisors is an integer number (7204017240).

Almost surely, 2^21612051717 is an apocalyptic number.

It is an amenable number.

21612051717 is a deficient number, since it is larger than the sum of its proper divisors (7204017243).

21612051717 is an equidigital number, since it uses as much as digits as its factorization.

21612051717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7204017242.

The product of its (nonzero) digits is 5880, while the sum is 33.

The spelling of 21612051717 in words is "twenty-one billion, six hundred twelve million, fifty-one thousand, seven hundred seventeen".