21120019517 has 2 divisors, whose sum is σ = 21120019518. Its totient is φ = 21120019516.

The previous prime is 21120019511. The next prime is 21120019541. The reversal of 21120019517 is 71591002112.

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., 16771804036 + 4348215481 = 129506^2 + 65941^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120019517 - 2²⁰ = 21118970941 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21120019517.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21120019511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560009758 + 10560009759.

It is an arithmetic number, because the mean of its divisors is an integer number (10560009759).

Almost surely, 2^21120019517 is an apocalyptic number.

It is an amenable number.

21120019517 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120019517 is an equidigital number, since it uses as much as digits as its factorization.

21120019517 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1260, while the sum is 29.

The spelling of 21120019517 in words is "twenty-one billion, one hundred twenty million, nineteen thousand, five hundred seventeen".