21365555211663 has 16 divisors (see below), whose sum is σ = 32293416785280. Its totient is φ = 12456032187744.

The previous prime is 21365555211577. The next prime is 21365555211761. The reversal of 21365555211663 is 36611255556312.

It is not a de Polignac number, because 21365555211663 - 2¹⁰ = 21365555210639 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21365555011663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14416703181 + ... + 14416704662.

It is an arithmetic number, because the mean of its divisors is an integer number (2018338549080).

Almost surely, 2^{21365555211663} is an apocalyptic number.

21365555211663 is a deficient number, since it is larger than the sum of its proper divisors (10927861573617).

21365555211663 is a wasteful number, since it uses less digits than its factorization.

21365555211663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28833407878.

The product of its digits is 4860000, while the sum is 51.

The spelling of 21365555211663 in words is "twenty-one trillion, three hundred sixty-five billion, five hundred fifty-five million, two hundred eleven thousand, six hundred sixty-three".