21111221012 has 24 divisors (see below), whose sum is σ = 42240003456. Its totient is φ = 9043903008.

The previous prime is 21111221009. The next prime is 21111221039. The reversal of 21111221012 is 21012211112.

It is a Harshad number since it is a multiple of its sum of digits (14).

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 87743 + ... + 223430.

It is an arithmetic number, because the mean of its divisors is an integer number (1760000144).

Almost surely, 2^21111221012 is an apocalyptic number.

It is an amenable number.

21111221012 is an abundant number, since it is smaller than the sum of its proper divisors (21128782444).

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

21111221012 is a wasteful number, since it uses less digits than its factorization.

21111221012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 313607 (or 313605 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21111221012 its reverse (21012211112), we get a palindrome (42123432124).

It can be divided in two parts, 211112 and 21012, that multiplied together give a palindrome (4435885344).

The spelling of 21111221012 in words is "twenty-one billion, one hundred eleven million, two hundred twenty-one thousand, twelve".