21011853663 has 12 divisors (see below), whose sum is σ = 30394901160. Its totient is φ = 13987388976.

The previous prime is 21011853659. The next prime is 21011853683. The reversal of 21011853663 is 36635811012.

21011853663 is a `hidden beast` number, since 2 + 1 + 0 + 118 + 536 + 6 + 3 = 666.

It is not a de Polignac number, because 21011853663 - 2² = 21011853659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011853683) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1702968 + ... + 1715261.

It is an arithmetic number, because the mean of its divisors is an integer number (2532908430).

Almost surely, 2^21011853663 is an apocalyptic number.

21011853663 is a deficient number, since it is larger than the sum of its proper divisors (9383047497).

21011853663 is a wasteful number, since it uses less digits than its factorization.

21011853663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3418918 (or 3418915 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The spelling of 21011853663 in words is "twenty-one billion, eleven million, eight hundred fifty-three thousand, six hundred sixty-three".