21500242145 has 32 divisors (see below), whose sum is σ = 26550830592. Its totient is φ = 16708833792.

The previous prime is 21500242117. The next prime is 21500242147. The reversal of 21500242145 is 54124200512.

It is a cyclic number.

It is not a de Polignac number, because 21500242145 - 2¹⁰ = 21500241121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21500242147) 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 in 31 ways as a sum of consecutive naturals, for example, 7404764 + ... + 7407666.

It is an arithmetic number, because the mean of its divisors is an integer number (829713456).

Almost surely, 2^21500242145 is an apocalyptic number.

It is an amenable number.

21500242145 is a deficient number, since it is larger than the sum of its proper divisors (5050588447).

21500242145 is a wasteful number, since it uses less digits than its factorization.

21500242145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3281.

The product of its (nonzero) digits is 3200, while the sum is 26.

Adding to 21500242145 its reverse (54124200512), we get a palindrome (75624442657).

The spelling of 21500242145 in words is "twenty-one billion, five hundred million, two hundred forty-two thousand, one hundred forty-five".