20661673 has 4 divisors (see below), whose sum is σ = 20696320. Its totient is φ = 20627028.

The previous prime is 20661643. The next prime is 20661689. The reversal of 20661673 is 37616602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 37616602 = 2 ⋅18808301.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20661673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20661643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16413 + ... + 17626.

It is an arithmetic number, because the mean of its divisors is an integer number (5174080).

Almost surely, 2^20661673 is an apocalyptic number.

It is an amenable number.

20661673 is a deficient number, since it is larger than the sum of its proper divisors (34647).

20661673 is an equidigital number, since it uses as much as digits as its factorization.

20661673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34646.

The product of its (nonzero) digits is 9072, while the sum is 31.

The square root of 20661673 is about 4545.5113023729. The cubic root of 20661673 is about 274.4027722367.

The spelling of 20661673 in words is "twenty million, six hundred sixty-one thousand, six hundred seventy-three".