20561121 has 20 divisors (see below), whose sum is σ = 35103552. Its totient is φ = 11748888.

The previous prime is 20561117. The next prime is 20561147. The reversal of 20561121 is 12116502.

It is not a de Polignac number, because 20561121 - 2² = 20561117 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20561094 and 20561103.

It is not an unprimeable number, because it can be changed into a prime (20561111) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 17565 + ... + 18698.

Almost surely, 2^20561121 is an apocalyptic number.

20561121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20561121 is a deficient number, since it is larger than the sum of its proper divisors (14542431).

20561121 is an equidigital number, since it uses as much as digits as its factorization.

20561121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36282 (or 36273 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 20561121 is about 4534.4372307928. The cubic root of 20561121 is about 273.9569124354.

Adding to 20561121 its reverse (12116502), we get a palindrome (32677623).

The spelling of 20561121 in words is "twenty million, five hundred sixty-one thousand, one hundred twenty-one".