21185767413 has 12 divisors (see below), whose sum is σ = 30604998060. Its totient is φ = 14122306176.

The previous prime is 21185767399. The next prime is 21185767453. The reversal of 21185767413 is 31476758112.

21185767413 is a `hidden beast` number, since 2 + 1 + 1 + 8 + 576 + 74 + 1 + 3 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 5779496529 + 15406270884 = 76023^2 + 124122^2 .

It is not a de Polignac number, because 21185767413 - 2⁴ = 21185767397 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21185767453) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 37668 + ... + 209261.

It is an arithmetic number, because the mean of its divisors is an integer number (2550416505).

Almost surely, 2^21185767413 is an apocalyptic number.

It is an amenable number.

21185767413 is a deficient number, since it is larger than the sum of its proper divisors (9419230647).

21185767413 is a wasteful number, since it uses less digits than its factorization.

21185767413 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 256468 (or 256465 counting only the distinct ones).

The product of its digits is 282240, while the sum is 45.

The spelling of 21185767413 in words is "twenty-one billion, one hundred eighty-five million, seven hundred sixty-seven thousand, four hundred thirteen".