21265242016 has 96 divisors (see below), whose sum is σ = 45207106560. Its totient is φ = 9814162176.

The previous prime is 21265242007. The next prime is 21265242017. The reversal of 21265242016 is 61024256212.

It is a super-3 number, since 3×21265242016³ (a number of 32 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21265242017) 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, 14300025 + ... + 14301511.

It is an arithmetic number, because the mean of its divisors is an integer number (470907360).

Almost surely, 2^21265242016 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21265242016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22603553280).

21265242016 is an abundant number, since it is smaller than the sum of its proper divisors (23941864544).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21265242016 is a wasteful number, since it uses less digits than its factorization.

21265242016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2106 (or 2098 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 31.

Adding to 21265242016 its reverse (61024256212), we get a palindrome (82289498228).

The spelling of 21265242016 in words is "twenty-one billion, two hundred sixty-five million, two hundred forty-two thousand, sixteen".