20520981 has 12 divisors (see below), whose sum is σ = 31921708. Its totient is φ = 12628224.

The previous prime is 20520971. The next prime is 20521001. The reversal of 20520981 is 18902502.

It can be written as a sum of positive squares in 2 ways, for example, as 3006756 + 17514225 = 1734^2 + 4185^2 .

It is not a de Polignac number, because 20520981 - 2¹⁴ = 20504597 is a prime.

It is a super-2 number, since 2×20520981² = 842221322404722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20520901) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 87580 + ... + 87813.

Almost surely, 2^20520981 is an apocalyptic number.

It is an amenable number.

20520981 is a deficient number, since it is larger than the sum of its proper divisors (11400727).

20520981 is a wasteful number, since it uses less digits than its factorization.

20520981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175412 (or 175409 counting only the distinct ones).

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

The square root of 20520981 is about 4530.0089403885. The cubic root of 20520981 is about 273.7785208290.

It can be divided in two parts, 205209 and 81, that multiplied together give a square (16621929 = 4077²).

The spelling of 20520981 in words is "twenty million, five hundred twenty thousand, nine hundred eighty-one".