21509316919 has 2 divisors, whose sum is σ = 21509316920. Its totient is φ = 21509316918.

The previous prime is 21509316901. The next prime is 21509316943. The reversal of 21509316919 is 91961390512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21509316919 - 2⁹ = 21509316407 is a prime.

It is a super-2 number, since 2×21509316919² (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 (21509316949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10754658459 + 10754658460.

It is an arithmetic number, because the mean of its divisors is an integer number (10754658460).

Almost surely, 2^21509316919 is an apocalyptic number.

21509316919 is a deficient number, since it is larger than the sum of its proper divisors (1).

21509316919 is an equidigital number, since it uses as much as digits as its factorization.

21509316919 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 131220, while the sum is 46.

The spelling of 21509316919 in words is "twenty-one billion, five hundred nine million, three hundred sixteen thousand, nine hundred nineteen".