21728930417 has 8 divisors (see below), whose sum is σ = 21900269160. Its totient is φ = 21558263040.

The previous prime is 21728930387. The next prime is 21728930429. The reversal of 21728930417 is 71403982712.

It can be written as a sum of positive squares in 4 ways, for example, as 6876389776 + 14852540641 = 82924^2 + 121871^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21728930417 - 2²² = 21724736113 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21728930017) 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, 102758 + ... + 232415.

It is an arithmetic number, because the mean of its divisors is an integer number (2737533645).

Almost surely, 2^21728930417 is an apocalyptic number.

It is an amenable number.

21728930417 is a deficient number, since it is larger than the sum of its proper divisors (171338743).

21728930417 is a wasteful number, since it uses less digits than its factorization.

21728930417 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335683.

The product of its (nonzero) digits is 169344, while the sum is 44.

The spelling of 21728930417 in words is "twenty-one billion, seven hundred twenty-eight million, nine hundred thirty thousand, four hundred seventeen".