21788779867 has 8 divisors (see below), whose sum is σ = 22456526400. Its totient is φ = 21129539904.

The previous prime is 21788779849. The next prime is 21788779871. The reversal of 21788779867 is 76897788712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21788779867 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21788779796 and 21788779805.

It is not an unprimeable number, because it can be changed into a prime (21788779807) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2121442 + ... + 2131687.

It is an arithmetic number, because the mean of its divisors is an integer number (2807065800).

Almost surely, 2^21788779867 is an apocalyptic number.

21788779867 is a deficient number, since it is larger than the sum of its proper divisors (667746533).

21788779867 is a wasteful number, since it uses less digits than its factorization.

21788779867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4253285.

The product of its digits is 132765696, while the sum is 70.

The spelling of 21788779867 in words is "twenty-one billion, seven hundred eighty-eight million, seven hundred seventy-nine thousand, eight hundred sixty-seven".