20981673 has 10 divisors (see below), whose sum is σ = 31343114. Its totient is φ = 13987728.

The previous prime is 20981671. The next prime is 20981677. The reversal of 20981673 is 37618902.

It can be written as a sum of positive squares in only one way, i.e., 16621929 + 4359744 = 4077^2 + 2088^2 .

It is not a de Polignac number, because 20981673 - 2¹ = 20981671 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20981671) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 129436 + ... + 129597.

Almost surely, 2^20981673 is an apocalyptic number.

It is an amenable number.

20981673 is a deficient number, since it is larger than the sum of its proper divisors (10361441).

20981673 is an equidigital number, since it uses as much as digits as its factorization.

20981673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259045 (or 259036 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 20981673 is about 4580.5756188497. The cubic root of 20981673 is about 275.8121358612.

The spelling of 20981673 in words is "twenty million, nine hundred eighty-one thousand, six hundred seventy-three".