21051566055 has 48 divisors (see below), whose sum is σ = 41607820800. Its totient is φ = 9754205184.

The previous prime is 21051566051. The next prime is 21051566057. The reversal of 21051566055 is 55066515012.

It is not a de Polignac number, because 21051566055 - 2² = 21051566051 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051566051) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1048455 + ... + 1068344.

It is an arithmetic number, because the mean of its divisors is an integer number (866829600).

Almost surely, 2^21051566055 is an apocalyptic number.

21051566055 is a deficient number, since it is larger than the sum of its proper divisors (20556254745).

21051566055 is a wasteful number, since it uses less digits than its factorization.

21051566055 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2116840 (or 2116837 counting only the distinct ones).

The product of its (nonzero) digits is 45000, while the sum is 36.

The spelling of 21051566055 in words is "twenty-one billion, fifty-one million, five hundred sixty-six thousand, fifty-five".