21165403249 has 16 divisors (see below), whose sum is σ = 21520152576. Its totient is φ = 20814181200.

The previous prime is 21165403219. The next prime is 21165403271. The reversal of 21165403249 is 94230456112.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21165403249 - 2¹³ = 21165395057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21165403219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9016894 + ... + 9019240.

It is an arithmetic number, because the mean of its divisors is an integer number (1345009536).

Almost surely, 2^21165403249 is an apocalyptic number.

It is an amenable number.

21165403249 is a deficient number, since it is larger than the sum of its proper divisors (354749327).

21165403249 is a wasteful number, since it uses less digits than its factorization.

21165403249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3036.

The product of its (nonzero) digits is 51840, while the sum is 37.

The spelling of 21165403249 in words is "twenty-one billion, one hundred sixty-five million, four hundred three thousand, two hundred forty-nine".