20981025 has 60 divisors (see below), whose sum is σ = 41906172. Its totient is φ = 10316160.

The previous prime is 20980987. The next prime is 20981027. The reversal of 20981025 is 52018902.

It can be written as a sum of positive squares in 6 ways, for example, as 2396304 + 18584721 = 1548^2 + 4311^2 .

It is not a de Polignac number, because 20981025 - 2⁹ = 20980513 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 20981025.

It is not an unprimeable number, because it can be changed into a prime (20981027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 25927 + ... + 26723.

Almost surely, 2^20981025 is an apocalyptic number.

20981025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20981025 is a deficient number, since it is larger than the sum of its proper divisors (20925147).

20981025 is a wasteful number, since it uses less digits than its factorization.

20981025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 832 (or 818 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 20981025 is about 4580.5048848353. The cubic root of 20981025 is about 275.8092964291.

Adding to 20981025 its reverse (52018902), we get a palindrome (72999927).

The spelling of 20981025 in words is "twenty million, nine hundred eighty-one thousand, twenty-five".