20115978 has 16 divisors (see below), whose sum is σ = 40456416. Its totient is φ = 6667920.

The previous prime is 20115971. The next prime is 20115983. The reversal of 20115978 is 87951102.

It is not an unprimeable number, because it can be changed into a prime (20115971) 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 7 ways as a sum of consecutive naturals, for example, 8176 + ... + 10347.

It is an arithmetic number, because the mean of its divisors is an integer number (2528526).

Almost surely, 2^20115978 is an apocalyptic number.

20115978 is an abundant number, since it is smaller than the sum of its proper divisors (20340438).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20115978 is a wasteful number, since it uses less digits than its factorization.

20115978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18709.

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 20115978 is about 4485.0839457027. The cubic root of 20115978 is about 271.9654385873.

The spelling of 20115978 in words is "twenty million, one hundred fifteen thousand, nine hundred seventy-eight".