21115666506446 has 48 divisors (see below), whose sum is σ = 34226807233920. Its totient is φ = 9759234386880.

The previous prime is 21115666506401. The next prime is 21115666506449. The reversal of 21115666506446 is 64460566651112.

It is a super-2 number, since 2×21115666506446² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115666506449) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22799756 + ... + 23707808.

It is an arithmetic number, because the mean of its divisors is an integer number (713058484040).

Almost surely, 2^{21115666506446} is an apocalyptic number.

21115666506446 is a deficient number, since it is larger than the sum of its proper divisors (13111140727474).

21115666506446 is a wasteful number, since it uses less digits than its factorization.

21115666506446 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 908841 (or 908818 counting only the distinct ones).

The product of its (nonzero) digits is 6220800, while the sum is 53.

The spelling of 21115666506446 in words is "twenty-one trillion, one hundred fifteen billion, six hundred sixty-six million, five hundred six thousand, four hundred forty-six".