20981361 has 4 divisors (see below), whose sum is σ = 27975152. Its totient is φ = 13987572.

The previous prime is 20981357. The next prime is 20981369. The reversal of 20981361 is 16318902.

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.

It is not a de Polignac number, because 20981361 - 2² = 20981357 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20981369) 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, 3496891 + ... + 3496896.

It is an arithmetic number, because the mean of its divisors is an integer number (6993788).

Almost surely, 2^20981361 is an apocalyptic number.

It is an amenable number.

20981361 is a deficient number, since it is larger than the sum of its proper divisors (6993791).

20981361 is an equidigital number, since it uses as much as digits as its factorization.

20981361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6993790.

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 20981361 is about 4580.5415618680. The cubic root of 20981361 is about 275.8107687345.

The spelling of 20981361 in words is "twenty million, nine hundred eighty-one thousand, three hundred sixty-one".