20978650871 has 4 divisors (see below), whose sum is σ = 20980607544. Its totient is φ = 20976694200.

The previous prime is 20978650817. The next prime is 20978650907. The reversal of 20978650871 is 17805687902.

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

It is a cyclic number.

It is not a de Polignac number, because 20978650871 - 2³⁰ = 19904909047 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20978650571) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 962165 + ... + 983726.

It is an arithmetic number, because the mean of its divisors is an integer number (5245151886).

Almost surely, 2^20978650871 is an apocalyptic number.

20978650871 is a deficient number, since it is larger than the sum of its proper divisors (1956673).

20978650871 is a wasteful number, since it uses less digits than its factorization.

20978650871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1956672.

The product of its (nonzero) digits is 1693440, while the sum is 53.

The spelling of 20978650871 in words is "twenty billion, nine hundred seventy-eight million, six hundred fifty thousand, eight hundred seventy-one".