20478561 has 16 divisors (see below), whose sum is σ = 28842240. Its totient is φ = 12888720.

The previous prime is 20478559. The next prime is 20478571. The reversal of 20478561 is 16587402.

It is not a de Polignac number, because 20478561 - 2¹ = 20478559 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20478541) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24846 + ... + 25656.

It is an arithmetic number, because the mean of its divisors is an integer number (1802640).

Almost surely, 2^20478561 is an apocalyptic number.

It is an amenable number.

20478561 is a deficient number, since it is larger than the sum of its proper divisors (8363679).

20478561 is a wasteful number, since it uses less digits than its factorization.

20478561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1276.

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 20478561 is about 4525.3244082607. The cubic root of 20478561 is about 273.5897433614.

The spelling of 20478561 in words is "twenty million, four hundred seventy-eight thousand, five hundred sixty-one".