21879046681 has 2 divisors, whose sum is σ = 21879046682. Its totient is φ = 21879046680.

The previous prime is 21879046643. The next prime is 21879046711. The reversal of 21879046681 is 18664097812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18357811081 + 3521235600 = 135491^2 + 59340^2 .

It is a cyclic number.

It is not a de Polignac number, because 21879046681 - 2²⁹ = 21342175769 is a prime.

It is a super-2 number, since 2×21879046681² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21879046621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10939523340 + 10939523341.

It is an arithmetic number, because the mean of its divisors is an integer number (10939523341).

Almost surely, 2^21879046681 is an apocalyptic number.

It is an amenable number.

21879046681 is a deficient number, since it is larger than the sum of its proper divisors (1).

21879046681 is an equidigital number, since it uses as much as digits as its factorization.

21879046681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1161216, while the sum is 52.

The spelling of 21879046681 in words is "twenty-one billion, eight hundred seventy-nine million, forty-six thousand, six hundred eighty-one".