21224101021 has 4 divisors (see below), whose sum is σ = 21224648700. Its totient is φ = 21223553344.

The previous prime is 21224100991. The next prime is 21224101057. The reversal of 21224101021 is 12010142212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5507717796 + 15716383225 = 74214^2 + 125365^2 .

It is a cyclic number.

It is not a de Polignac number, because 21224101021 - 2⁷ = 21224100893 is a prime.

It is a super-2 number, since 2×21224101021² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21224100986 and 21224101004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21224101081) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 210886 + ... + 294823.

It is an arithmetic number, because the mean of its divisors is an integer number (5306162175).

Almost surely, 2^21224101021 is an apocalyptic number.

It is an amenable number.

21224101021 is a deficient number, since it is larger than the sum of its proper divisors (547679).

21224101021 is an equidigital number, since it uses as much as digits as its factorization.

21224101021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 547678.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21224101021 its reverse (12010142212), we get a palindrome (33234243233).

The spelling of 21224101021 in words is "twenty-one billion, two hundred twenty-four million, one hundred one thousand, twenty-one".