20815517816078 has 4 divisors (see below), whose sum is σ = 31223276724120. Its totient is φ = 10407758908038.

The previous prime is 20815517816059. The next prime is 20815517816141. The reversal of 20815517816078 is 87061871551802.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5203879454018 + ... + 5203879454021.

It is an arithmetic number, because the mean of its divisors is an integer number (7805819181030).

Almost surely, 2^{20815517816078} is an apocalyptic number.

20815517816078 is a deficient number, since it is larger than the sum of its proper divisors (10407758908042).

20815517816078 is a wasteful number, since it uses less digits than its factorization.

20815517816078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10407758908041.

The product of its (nonzero) digits is 7526400, while the sum is 59.

The spelling of 20815517816078 in words is "twenty trillion, eight hundred fifteen billion, five hundred seventeen million, eight hundred sixteen thousand, seventy-eight".