21421512017 has 4 divisors (see below), whose sum is σ = 21456119280. Its totient is φ = 21386904756.

The previous prime is 21421511999. The next prime is 21421512043. The reversal of 21421512017 is 71021512412.

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 21421512017 - 2²⁴ = 21404734801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21421512067) 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, 17302703 + ... + 17303940.

It is an arithmetic number, because the mean of its divisors is an integer number (5364029820).

Almost surely, 2^21421512017 is an apocalyptic number.

It is an amenable number.

21421512017 is a deficient number, since it is larger than the sum of its proper divisors (34607263).

21421512017 is an equidigital number, since it uses as much as digits as its factorization.

21421512017 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34607262.

The product of its (nonzero) digits is 1120, while the sum is 26.

The spelling of 21421512017 in words is "twenty-one billion, four hundred twenty-one million, five hundred twelve thousand, seventeen".