21705012012 has 24 divisors (see below), whose sum is σ = 50771336112. Its totient is φ = 7216960000.

The previous prime is 21705011947. The next prime is 21705012041. The reversal of 21705012012 is 21021050712.

It is a super-2 number, since 2×21705012012² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21705012012.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2250489 + ... + 2260112.

It is an arithmetic number, because the mean of its divisors is an integer number (2115472338).

Almost surely, 2^21705012012 is an apocalyptic number.

It is an amenable number.

21705012012 is an abundant number, since it is smaller than the sum of its proper divisors (29066324100).

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

21705012012 is a wasteful number, since it uses less digits than its factorization.

21705012012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4511009 (or 4511007 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 21.

Adding to 21705012012 its reverse (21021050712), we get a palindrome (42726062724).

The spelling of 21705012012 in words is "twenty-one billion, seven hundred five million, twelve thousand, twelve".