21563866426 has 8 divisors (see below), whose sum is σ = 32709235860. Its totient is φ = 10660787808.

The previous prime is 21563866391. The next prime is 21563866469. The reversal of 21563866426 is 62466836512.

It can be written as a sum of positive squares in 2 ways, for example, as 17663739025 + 3900127401 = 132905^2 + 62451^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 21563866426.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60572481 + ... + 60572836.

Almost surely, 2^21563866426 is an apocalyptic number.

21563866426 is a deficient number, since it is larger than the sum of its proper divisors (11145369434).

21563866426 is a wasteful number, since it uses less digits than its factorization.

21563866426 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121145408.

The product of its digits is 2488320, while the sum is 49.

The spelling of 21563866426 in words is "twenty-one billion, five hundred sixty-three million, eight hundred sixty-six thousand, four hundred twenty-six".