20561320 has 32 divisors (see below), whose sum is σ = 49822920. Its totient is φ = 7591680.

The previous prime is 20561311. The next prime is 20561327. The reversal of 20561320 is 2316502.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 5769604 + 14791716 = 2402^2 + 3846^2 .

It is not an unprimeable number, because it can be changed into a prime (20561327) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19251 + ... + 20290.

Almost surely, 2^20561320 is an apocalyptic number.

20561320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20561320 is an abundant number, since it is smaller than the sum of its proper divisors (29261600).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20561320 is a wasteful number, since it uses less digits than its factorization.

20561320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39565 (or 39561 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 20561320 is about 4534.4591739258. The cubic root of 20561320 is about 273.9577962596.

Adding to 20561320 its reverse (2316502), we get a palindrome (22877822).

The spelling of 20561320 in words is "twenty million, five hundred sixty-one thousand, three hundred twenty".