16656021181 has 2 divisors, whose sum is σ = 16656021182. Its totient is φ = 16656021180.

The previous prime is 16656021139. The next prime is 16656021227. The reversal of 16656021181 is 18112065661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9621844281 + 7034176900 = 98091^2 + 83870^2 .

It is a cyclic number.

It is not a de Polignac number, because 16656021181 - 2¹⁷ = 16655890109 is a prime.

It is a super-2 number, since 2×16656021181² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 16656021181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16656001181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8328010590 + 8328010591.

It is an arithmetic number, because the mean of its divisors is an integer number (8328010591).

Almost surely, 2^16656021181 is an apocalyptic number.

It is an amenable number.

16656021181 is a deficient number, since it is larger than the sum of its proper divisors (1).

16656021181 is an equidigital number, since it uses as much as digits as its factorization.

16656021181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 37.

The spelling of 16656021181 in words is "sixteen billion, six hundred fifty-six million, twenty-one thousand, one hundred eighty-one".