20478515 has 4 divisors (see below), whose sum is σ = 24574224. Its totient is φ = 16382808.

The previous prime is 20478509. The next prime is 20478539. The reversal of 20478515 is 51587402.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20478515 - 2⁴ = 20478499 is a prime.

It is a Duffinian number.

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, 2047847 + ... + 2047856.

It is an arithmetic number, because the mean of its divisors is an integer number (6143556).

Almost surely, 2^20478515 is an apocalyptic number.

20478515 is a deficient number, since it is larger than the sum of its proper divisors (4095709).

20478515 is an equidigital number, since it uses as much as digits as its factorization.

20478515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4095708.

The product of its (nonzero) digits is 11200, while the sum is 32.

The square root of 20478515 is about 4525.3193257493. The cubic root of 20478515 is about 273.5895385108.

The spelling of 20478515 in words is "twenty million, four hundred seventy-eight thousand, five hundred fifteen".