21500540066 has 16 divisors (see below), whose sum is σ = 32428844448. Its totient is φ = 10690963200.

The previous prime is 21500540063. The next prime is 21500540069. The reversal of 21500540066 is 66004500512.

It is an interprime number because it is at equal distance from previous prime (21500540063) and next prime (21500540069).

It is not an unprimeable number, because it can be changed into a prime (21500540063) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1417181 + ... + 1432271.

It is an arithmetic number, because the mean of its divisors is an integer number (2026802778).

Almost surely, 2^21500540066 is an apocalyptic number.

21500540066 is a deficient number, since it is larger than the sum of its proper divisors (10928304382).

21500540066 is a wasteful number, since it uses less digits than its factorization.

21500540066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18977.

The product of its (nonzero) digits is 7200, while the sum is 29.

The spelling of 21500540066 in words is "twenty-one billion, five hundred million, five hundred forty thousand, sixty-six".