21643426671066 has 12 divisors (see below), whose sum is σ = 46894091120682. Its totient is φ = 7214475557016.

The previous prime is 21643426671007. The next prime is 21643426671109. The reversal of 21643426671066 is 66017662434612.

It is a happy number.

21643426671066 is a `hidden beast` number, since 2 + 16 + 43 + 426 + 67 + 106 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 21465346891041 + 178079780025 = 4633071^2 + 421995^2 .

It is a super-2 number, since 2×21643426671066² (a number of 27 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 601206296401 + ... + 601206296436.

Almost surely, 2^{21643426671066} is an apocalyptic number.

21643426671066 is an abundant number, since it is smaller than the sum of its proper divisors (25250664449616).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21643426671066 is a wasteful number, since it uses less digits than its factorization.

21643426671066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1202412592845 (or 1202412592842 counting only the distinct ones).

The product of its (nonzero) digits is 10450944, while the sum is 54.

The spelling of 21643426671066 in words is "twenty-one trillion, six hundred forty-three billion, four hundred twenty-six million, six hundred seventy-one thousand, sixty-six".