21511648613 has 24 divisors (see below), whose sum is σ = 27251524440. Its totient is φ = 16828922880.

The previous prime is 21511648607. The next prime is 21511648643. The reversal of 21511648613 is 31684611512.

It can be written as a sum of positive squares in 4 ways, for example, as 1772241604 + 19739407009 = 42098^2 + 140497^2 .

It is not a de Polignac number, because 21511648613 - 2⁶ = 21511648549 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21511648643) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 133028 + ... + 246413.

It is an arithmetic number, because the mean of its divisors is an integer number (1135480185).

Almost surely, 2^21511648613 is an apocalyptic number.

It is an amenable number.

21511648613 is a deficient number, since it is larger than the sum of its proper divisors (5739875827).

21511648613 is a wasteful number, since it uses less digits than its factorization.

21511648613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 379557 (or 379550 counting only the distinct ones).

The product of its digits is 34560, while the sum is 38.

The spelling of 21511648613 in words is "twenty-one billion, five hundred eleven million, six hundred forty-eight thousand, six hundred thirteen".