20478021 has 4 divisors (see below), whose sum is σ = 27304032. Its totient is φ = 13652012.

The previous prime is 20477987. The next prime is 20478023. The reversal of 20478021 is 12087402.

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.

It is a cyclic number.

It is not a de Polignac number, because 20478021 - 2⁶ = 20477957 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20477982 and 20478000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20478023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3413001 + ... + 3413006.

It is an arithmetic number, because the mean of its divisors is an integer number (6826008).

Almost surely, 2^20478021 is an apocalyptic number.

It is an amenable number.

20478021 is a deficient number, since it is larger than the sum of its proper divisors (6826011).

20478021 is an equidigital number, since it uses as much as digits as its factorization.

20478021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6826010.

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 20478021 is about 4525.2647436366. The cubic root of 20478021 is about 273.5873385740.

The spelling of 20478021 in words is "twenty million, four hundred seventy-eight thousand, twenty-one".