21201264016 has 20 divisors (see below), whose sum is σ = 41092263900. Its totient is φ = 10596808832.

The previous prime is 21201263987. The next prime is 21201264061. The reversal of 21201264016 is 61046210212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 6448732416 + 14752531600 = 80304^2 + 121460^2 .

It is a super-2 number, since 2×21201264016² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 192931 + ... + 282178.

It is an arithmetic number, because the mean of its divisors is an integer number (2054613195).

Almost surely, 2^21201264016 is an apocalyptic number.

It is an amenable number.

21201264016 is a deficient number, since it is larger than the sum of its proper divisors (19890999884).

21201264016 is a wasteful number, since it uses less digits than its factorization.

21201264016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 477906 (or 477900 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 25.

Adding to 21201264016 its reverse (61046210212), we get a palindrome (82247474228).

The spelling of 21201264016 in words is "twenty-one billion, two hundred one million, two hundred sixty-four thousand, sixteen".