21879139797 has 10 divisors (see below), whose sum is σ = 32683653398. Its totient is φ = 14586093144.

The previous prime is 21879139769. The next prime is 21879139801. The reversal of 21879139797 is 79793197812.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21876184836 + 2954961 = 147906^2 + 1719^2 .

It is not a de Polignac number, because 21879139797 - 2¹⁰ = 21879138773 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 (21879139727) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 135056338 + ... + 135056499.

Almost surely, 2^21879139797 is an apocalyptic number.

21879139797 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21879139797 is a deficient number, since it is larger than the sum of its proper divisors (10804513601).

21879139797 is an equidigital number, since it uses as much as digits as its factorization.

21879139797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270112849 (or 270112840 counting only the distinct ones).

The product of its digits is 12002256, while the sum is 63.

The spelling of 21879139797 in words is "twenty-one billion, eight hundred seventy-nine million, one hundred thirty-nine thousand, seven hundred ninety-seven".