21663851727 has 24 divisors (see below), whose sum is σ = 33722443056. Its totient is φ = 12334629888.

The previous prime is 21663851717. The next prime is 21663851747. The reversal of 21663851727 is 72715836612.

It is not a de Polignac number, because 21663851727 - 2¹² = 21663847631 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21663851717) 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, 225298 + ... + 306735.

It is an arithmetic number, because the mean of its divisors is an integer number (1405101794).

Almost surely, 2^21663851727 is an apocalyptic number.

21663851727 is a deficient number, since it is larger than the sum of its proper divisors (12058591329).

21663851727 is a wasteful number, since it uses less digits than its factorization.

21663851727 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 532327 (or 532320 counting only the distinct ones).

The product of its digits is 846720, while the sum is 48.

The spelling of 21663851727 in words is "twenty-one billion, six hundred sixty-three million, eight hundred fifty-one thousand, seven hundred twenty-seven".