21101002421 has 4 divisors (see below), whose sum is σ = 21136112844. Its totient is φ = 21065892000.

The previous prime is 21101002393. The next prime is 21101002487. The reversal of 21101002421 is 12420010112.

It is a happy number.

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 13290861796 + 7810140625 = 115286^2 + 88375^2 .

It is a cyclic number.

It is not a de Polignac number, because 21101002421 - 2²⁶ = 21033893557 is a prime.

It is a super-2 number, since 2×21101002421² (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 = 21101002396 and 21101002405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101052421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17554310 + ... + 17555511.

It is an arithmetic number, because the mean of its divisors is an integer number (5284028211).

Almost surely, 2^21101002421 is an apocalyptic number.

It is an amenable number.

21101002421 is a deficient number, since it is larger than the sum of its proper divisors (35110423).

21101002421 is an equidigital number, since it uses as much as digits as its factorization.

21101002421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35110422.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21101002421 its reverse (12420010112), we get a palindrome (33521012533).

The spelling of 21101002421 in words is "twenty-one billion, one hundred one million, two thousand, four hundred twenty-one".