21123009079 has 2 divisors, whose sum is σ = 21123009080. Its totient is φ = 21123009078.

The previous prime is 21123009053. The next prime is 21123009101. The reversal of 21123009079 is 97090032112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21123009079 - 2²¹ = 21120911927 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21123009379) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561504539 + 10561504540.

It is an arithmetic number, because the mean of its divisors is an integer number (10561504540).

Almost surely, 2^21123009079 is an apocalyptic number.

21123009079 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123009079 is an equidigital number, since it uses as much as digits as its factorization.

21123009079 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6804, while the sum is 34.

The spelling of 21123009079 in words is "twenty-one billion, one hundred twenty-three million, nine thousand, seventy-nine".