21879537161 has 2 divisors, whose sum is σ = 21879537162. Its totient is φ = 21879537160.

The previous prime is 21879537139. The next prime is 21879537227. The reversal of 21879537161 is 16173597812.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12841422400 + 9038114761 = 113320^2 + 95069^2 .

It is a cyclic number.

It is not a de Polignac number, because 21879537161 - 2³⁰ = 20805795337 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21879537131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10939768580 + 10939768581.

It is an arithmetic number, because the mean of its divisors is an integer number (10939768581).

Almost surely, 2^21879537161 is an apocalyptic number.

It is an amenable number.

21879537161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21879537161 is an equidigital number, since it uses as much as digits as its factorization.

21879537161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 635040, while the sum is 50.

The spelling of 21879537161 in words is "twenty-one billion, eight hundred seventy-nine million, five hundred thirty-seven thousand, one hundred sixty-one".