21155055079 has 2 divisors, whose sum is σ = 21155055080. Its totient is φ = 21155055078.

The previous prime is 21155055013. The next prime is 21155055109. The reversal of 21155055079 is 97055055112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21155055079 - 2¹⁵ = 21155022311 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21155056079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577527539 + 10577527540.

It is an arithmetic number, because the mean of its divisors is an integer number (10577527540).

Almost surely, 2^21155055079 is an apocalyptic number.

21155055079 is a deficient number, since it is larger than the sum of its proper divisors (1).

21155055079 is an equidigital number, since it uses as much as digits as its factorization.

21155055079 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 78750, while the sum is 40.

The spelling of 21155055079 in words is "twenty-one billion, one hundred fifty-five million, fifty-five thousand, seventy-nine".