20664161 has 16 divisors (see below), whose sum is σ = 24385536. Its totient is φ = 17144016.

The previous prime is 20664139. The next prime is 20664239. The reversal of 20664161 is 16146602.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 20664161 - 2¹⁴ = 20647777 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20664161.

It is not an unprimeable number, because it can be changed into a prime (20664131) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34910 + ... + 35496.

It is an arithmetic number, because the mean of its divisors is an integer number (1524096).

Almost surely, 2^20664161 is an apocalyptic number.

It is an amenable number.

20664161 is a deficient number, since it is larger than the sum of its proper divisors (3721375).

20664161 is a wasteful number, since it uses less digits than its factorization.

20664161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 748.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 20664161 is about 4545.7849707174. The cubic root of 20664161 is about 274.4137859736.

The spelling of 20664161 in words is "twenty million, six hundred sixty-four thousand, one hundred sixty-one".