21325513666 has 16 divisors (see below), whose sum is σ = 32376052800. Its totient is φ = 10533991248.

The previous prime is 21325513663. The next prime is 21325513673. The reversal of 21325513666 is 66631552312.

It is not an unprimeable number, because it can be changed into a prime (21325513661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37221 + ... + 209848.

It is an arithmetic number, because the mean of its divisors is an integer number (2023503300).

Almost surely, 2^21325513666 is an apocalyptic number.

21325513666 is a deficient number, since it is larger than the sum of its proper divisors (11050539134).

21325513666 is a wasteful number, since it uses less digits than its factorization.

21325513666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247593.

The product of its digits is 194400, while the sum is 40.

The spelling of 21325513666 in words is "twenty-one billion, three hundred twenty-five million, five hundred thirteen thousand, six hundred sixty-six".