21506065664463 has 24 divisors (see below), whose sum is σ = 31458909081600. Its totient is φ = 14155273561104.

The previous prime is 21506065664453. The next prime is 21506065664467. The reversal of 21506065664463 is 36446656060512.

21506065664463 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 60 + 65 + 6 + 64 + 463 = 666.

It is not a de Polignac number, because 21506065664463 - 2¹⁷ = 21506065533391 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21506065664467) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15937158 + ... + 17233836.

It is an arithmetic number, because the mean of its divisors is an integer number (1310787878400).

Almost surely, 2^{21506065664463} is an apocalyptic number.

21506065664463 is a deficient number, since it is larger than the sum of its proper divisors (9952843417137).

21506065664463 is a wasteful number, since it uses less digits than its factorization.

21506065664463 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1320091 (or 1320088 counting only the distinct ones).

The product of its (nonzero) digits is 18662400, while the sum is 54.

The spelling of 21506065664463 in words is "twenty-one trillion, five hundred six billion, sixty-five million, six hundred sixty-four thousand, four hundred sixty-three".