20121515 has 4 divisors (see below), whose sum is σ = 24145824. Its totient is φ = 16097208.

The previous prime is 20121467. The next prime is 20121533. The reversal of 20121515 is 51512102.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51512102 = 2 ⋅25756051.

It is a cyclic number.

It is not a de Polignac number, because 20121515 - 2¹⁰ = 20120491 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20121493 and 20121502.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2012147 + ... + 2012156.

It is an arithmetic number, because the mean of its divisors is an integer number (6036456).

Almost surely, 2^20121515 is an apocalyptic number.

20121515 is a deficient number, since it is larger than the sum of its proper divisors (4024309).

20121515 is an equidigital number, since it uses as much as digits as its factorization.

20121515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4024308.

The product of its (nonzero) digits is 100, while the sum is 17.

The square root of 20121515 is about 4485.7011715004. The cubic root of 20121515 is about 271.9903894745.

Adding to 20121515 its reverse (51512102), we get a palindrome (71633617).

The spelling of 20121515 in words is "twenty million, one hundred twenty-one thousand, five hundred fifteen".