21011221012 has 6 divisors (see below), whose sum is σ = 36769636778. Its totient is φ = 10505610504.

The previous prime is 21011220983. The next prime is 21011221019. The reversal of 21011221012 is 21012211012.

It can be written as a sum of positive squares in only one way, i.e., 17871411856 + 3139809156 = 133684^2 + 56034^2 .

It is a super-2 number, since 2×21011221012² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21011220983 and 21011221001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011221019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2626402623 + ... + 2626402630.

Almost surely, 2^21011221012 is an apocalyptic number.

It is an amenable number.

21011221012 is a deficient number, since it is larger than the sum of its proper divisors (15758415766).

21011221012 is a wasteful number, since it uses less digits than its factorization.

21011221012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5252805257 (or 5252805255 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21011221012 its reverse (21012211012), we get a palindrome (42023432024).

The spelling of 21011221012 in words is "twenty-one billion, eleven million, two hundred twenty-one thousand, twelve".