21124642117 has 2 divisors, whose sum is σ = 21124642118. Its totient is φ = 21124642116.

The previous prime is 21124642087. The next prime is 21124642157. The reversal of 21124642117 is 71124642112.

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., 12093180961 + 9031461156 = 109969^2 + 95034^2 .

It is a cyclic number.

It is not a de Polignac number, because 21124642117 - 2³¹ = 18977158469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21124642157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10562321058 + 10562321059.

It is an arithmetic number, because the mean of its divisors is an integer number (10562321059).

Almost surely, 2^21124642117 is an apocalyptic number.

It is an amenable number.

21124642117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21124642117 is an equidigital number, since it uses as much as digits as its factorization.

21124642117 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5376, while the sum is 31.

The spelling of 21124642117 in words is "twenty-one billion, one hundred twenty-four million, six hundred forty-two thousand, one hundred seventeen".