21667155671668 has 24 divisors (see below), whose sum is σ = 41604712564968. Its totient is φ = 9811542189696.

The previous prime is 21667155671663. The next prime is 21667155671671. The reversal of 21667155671668 is 86617655176612.

It can be written as a sum of positive squares in 4 ways, for example, as 2490708927204 + 19176446744464 = 1578198^2 + 4379092^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21667155671663) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3930903571 + ... + 3930909082.

It is an arithmetic number, because the mean of its divisors is an integer number (1733529690207).

Almost surely, 2^{21667155671668} is an apocalyptic number.

It is an amenable number.

21667155671668 is a deficient number, since it is larger than the sum of its proper divisors (19937556893300).

21667155671668 is a wasteful number, since it uses less digits than its factorization.

21667155671668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7861812723 (or 7861812721 counting only the distinct ones).

The product of its digits is 152409600, while the sum is 67.

The spelling of 21667155671668 in words is "twenty-one trillion, six hundred sixty-seven billion, one hundred fifty-five million, six hundred seventy-one thousand, six hundred sixty-eight".