21001107985 has 32 divisors (see below), whose sum is σ = 29840412672. Its totient is φ = 13987572480.

The previous prime is 21001107971. The next prime is 21001107989. The reversal of 21001107985 is 58970110012.

It is a happy number.

It is not a de Polignac number, because 21001107985 - 2³¹ = 18853624337 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21001107985.

It is not an unprimeable number, because it can be changed into a prime (21001107989) 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 31 ways as a sum of consecutive naturals, for example, 24834 + ... + 206443.

It is an arithmetic number, because the mean of its divisors is an integer number (932512896).

Almost surely, 2^21001107985 is an apocalyptic number.

It is an amenable number.

21001107985 is a deficient number, since it is larger than the sum of its proper divisors (8839304687).

21001107985 is a wasteful number, since it uses less digits than its factorization.

21001107985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 231433.

The product of its (nonzero) digits is 5040, while the sum is 34.

Adding to 21001107985 its reverse (58970110012), we get a palindrome (79971217997).

The spelling of 21001107985 in words is "twenty-one billion, one million, one hundred seven thousand, nine hundred eighty-five".