21664460142266 has 4 divisors (see below), whose sum is σ = 32496690213402. Its totient is φ = 10832230071132.

The previous prime is 21664460142233. The next prime is 21664460142293. The reversal of 21664460142266 is 66224106446612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 21105561858241 + 558898284025 = 4594079^2 + 747595^2 .

It is a super-2 number, since 2×21664460142266² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5416115035565 + ... + 5416115035568.

Almost surely, 2^{21664460142266} is an apocalyptic number.

21664460142266 is a deficient number, since it is larger than the sum of its proper divisors (10832230071136).

21664460142266 is a wasteful number, since it uses less digits than its factorization.

21664460142266 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10832230071135.

The product of its (nonzero) digits is 3981312, while the sum is 50.

Adding to 21664460142266 its reverse (66224106446612), we get a palindrome (87888566588878).

The spelling of 21664460142266 in words is "twenty-one trillion, six hundred sixty-four billion, four hundred sixty million, one hundred forty-two thousand, two hundred sixty-six".