20978381869 has 4 divisors (see below), whose sum is σ = 21033156096. Its totient is φ = 20923607644.

The previous prime is 20978381797. The next prime is 20978381873. The reversal of 20978381869 is 96818387902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 96818387902 = 2 ⋅48409193951.

It is a cyclic number.

It is not a de Polignac number, because 20978381869 - 2³³ = 12388447277 is a prime.

It is a super-2 number, since 2×20978381869² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20978381899) 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, 27386539 + ... + 27387304.

It is an arithmetic number, because the mean of its divisors is an integer number (5258289024).

Almost surely, 2^20978381869 is an apocalyptic number.

It is an amenable number.

20978381869 is a deficient number, since it is larger than the sum of its proper divisors (54774227).

20978381869 is an equidigital number, since it uses as much as digits as its factorization.

20978381869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54774226.

The product of its (nonzero) digits is 10450944, while the sum is 61.

The spelling of 20978381869 in words is "twenty billion, nine hundred seventy-eight million, three hundred eighty-one thousand, eight hundred sixty-nine".