21523785945 has 16 divisors (see below), whose sum is σ = 34440887232. Its totient is φ = 11478409280.

The previous prime is 21523785931. The next prime is 21523785947. The reversal of 21523785945 is 54958732512.

It is not a de Polignac number, because 21523785945 - 2¹⁶ = 21523720409 is a prime.

It is a super-2 number, since 2×21523785945² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21523785947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 154654 + ... + 258776.

It is an arithmetic number, because the mean of its divisors is an integer number (2152555452).

Almost surely, 2^21523785945 is an apocalyptic number.

It is an amenable number.

21523785945 is a deficient number, since it is larger than the sum of its proper divisors (12917101287).

21523785945 is a wasteful number, since it uses less digits than its factorization.

21523785945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117912.

The product of its digits is 3024000, while the sum is 51.

The spelling of 21523785945 in words is "twenty-one billion, five hundred twenty-three million, seven hundred eighty-five thousand, nine hundred forty-five".