21405328617 has 8 divisors (see below), whose sum is σ = 30042566560. Its totient is φ = 13519154880.

The previous prime is 21405328537. The next prime is 21405328687. The reversal of 21405328617 is 71682350412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21405328617 - 2⁸ = 21405328361 is a prime.

It is a super-3 number, since 3×21405328617³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21405328687) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 187765984 + ... + 187766097.

It is an arithmetic number, because the mean of its divisors is an integer number (3755320820).

Almost surely, 2^21405328617 is an apocalyptic number.

It is an amenable number.

21405328617 is a deficient number, since it is larger than the sum of its proper divisors (8637237943).

21405328617 is a wasteful number, since it uses less digits than its factorization.

21405328617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 375532103.

The product of its (nonzero) digits is 80640, while the sum is 39.

The spelling of 21405328617 in words is "twenty-one billion, four hundred five million, three hundred twenty-eight thousand, six hundred seventeen".