21121221012 has 96 divisors (see below), whose sum is σ = 52093601280. Its totient is φ = 6653137920.

The previous prime is 21121221001. The next prime is 21121221013. The reversal of 21121221012 is 21012212112.

It is a super-2 number, since 2×21121221012² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21121220982 and 21121221000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121221013) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2054878 + ... + 2065130.

It is an arithmetic number, because the mean of its divisors is an integer number (542641680).

Almost surely, 2^21121221012 is an apocalyptic number.

It is an amenable number.

21121221012 is an abundant number, since it is smaller than the sum of its proper divisors (30972380268).

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

21121221012 is a wasteful number, since it uses less digits than its factorization.

21121221012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10433 (or 10431 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21121221012 its reverse (21012212112), we get a palindrome (42133433124).

The spelling of 21121221012 in words is "twenty-one billion, one hundred twenty-one million, two hundred twenty-one thousand, twelve".