20512121 has 4 divisors (see below), whose sum is σ = 23442432. Its totient is φ = 17581812.

The previous prime is 20512087. The next prime is 20512139. The reversal of 20512121 is 12121502.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12121502 = 2 ⋅6060751.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20512121 is a prime.

It is a Duffinian number.

20512121 is a modest number, since divided by 2121 gives 2051 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 20512096 and 20512105.

It is not an unprimeable number, because it can be changed into a prime (20512181) 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, 1465145 + ... + 1465158.

It is an arithmetic number, because the mean of its divisors is an integer number (5860608).

Almost surely, 2^20512121 is an apocalyptic number.

It is an amenable number.

20512121 is a deficient number, since it is larger than the sum of its proper divisors (2930311).

20512121 is an equidigital number, since it uses as much as digits as its factorization.

20512121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2930310.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 20512121 is about 4529.0309117956. The cubic root of 20512121 is about 273.7391135694.

Adding to 20512121 its reverse (12121502), we get a palindrome (32633623).

The spelling of 20512121 in words is "twenty million, five hundred twelve thousand, one hundred twenty-one".