20581978 has 8 divisors (see below), whose sum is σ = 32497920. Its totient is φ = 9749340.

The previous prime is 20581961. The next prime is 20581991. The reversal of 20581978 is 87918502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 20581978.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 270778 + ... + 270853.

It is an arithmetic number, because the mean of its divisors is an integer number (4062240).

Almost surely, 2^20581978 is an apocalyptic number.

20581978 is a deficient number, since it is larger than the sum of its proper divisors (11915942).

20581978 is a wasteful number, since it uses less digits than its factorization.

20581978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 541652.

The product of its (nonzero) digits is 40320, while the sum is 40.

The square root of 20581978 is about 4536.7364922376. The cubic root of 20581978 is about 274.0495142017.

The spelling of 20581978 in words is "twenty million, five hundred eighty-one thousand, nine hundred seventy-eight".