21251235079 has 2 divisors, whose sum is σ = 21251235080. Its totient is φ = 21251235078.

The previous prime is 21251235073. The next prime is 21251235143. The reversal of 21251235079 is 97053215212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21251235079 - 2¹⁵ = 21251202311 is a prime.

It is a super-2 number, since 2×21251235079² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21251235073) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625617539 + 10625617540.

It is an arithmetic number, because the mean of its divisors is an integer number (10625617540).

Almost surely, 2^21251235079 is an apocalyptic number.

21251235079 is a deficient number, since it is larger than the sum of its proper divisors (1).

21251235079 is an equidigital number, since it uses as much as digits as its factorization.

21251235079 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 37800, while the sum is 37.

The spelling of 21251235079 in words is "twenty-one billion, two hundred fifty-one million, two hundred thirty-five thousand, seventy-nine".