20681978 has 16 divisors (see below), whose sum is σ = 32153760. Its totient is φ = 9970896.

The previous prime is 20681957. The next prime is 20681993. The reversal of 20681978 is 87918602.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4601 + ... + 7907.

It is an arithmetic number, because the mean of its divisors is an integer number (2009610).

Almost surely, 2^20681978 is an apocalyptic number.

20681978 is a deficient number, since it is larger than the sum of its proper divisors (11471782).

20681978 is a wasteful number, since it uses less digits than its factorization.

20681978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3421.

The product of its (nonzero) digits is 48384, while the sum is 41.

The square root of 20681978 is about 4547.7442760120. The cubic root of 20681978 is about 274.4926314347.

The spelling of 20681978 in words is "twenty million, six hundred eighty-one thousand, nine hundred seventy-eight".