20981173 has 4 divisors (see below), whose sum is σ = 21016800. Its totient is φ = 20945548.

The previous prime is 20981153. The next prime is 20981189. The reversal of 20981173 is 37118902.

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: 37118902 = 2 ⋅18559451.

It is a cyclic number.

It is not a de Polignac number, because 20981173 - 2¹³ = 20972981 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20981143) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16915 + ... + 18112.

It is an arithmetic number, because the mean of its divisors is an integer number (5254200).

Almost surely, 2^20981173 is an apocalyptic number.

It is an amenable number.

20981173 is a deficient number, since it is larger than the sum of its proper divisors (35627).

20981173 is an equidigital number, since it uses as much as digits as its factorization.

20981173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35626.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 20981173 is about 4580.5210402311. The cubic root of 20981173 is about 275.8099449465.

The spelling of 20981173 in words is "twenty million, nine hundred eighty-one thousand, one hundred seventy-three".