21066340664 has 8 divisors (see below), whose sum is σ = 39499388760. Its totient is φ = 10533170328.

The previous prime is 21066340661. The next prime is 21066340693. The reversal of 21066340664 is 46604366012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21066340661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1316646284 + ... + 1316646299.

It is an arithmetic number, because the mean of its divisors is an integer number (4937423595).

Almost surely, 2^21066340664 is an apocalyptic number.

It is an amenable number.

21066340664 is a deficient number, since it is larger than the sum of its proper divisors (18433048096).

21066340664 is a wasteful number, since it uses less digits than its factorization.

21066340664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2633292589 (or 2633292585 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 38.

The spelling of 21066340664 in words is "twenty-one billion, sixty-six million, three hundred forty thousand, six hundred sixty-four".