21121002253421 has 4 divisors (see below), whose sum is σ = 24138288289632. Its totient is φ = 18103716217212.

The previous prime is 21121002253409. The next prime is 21121002253499. The reversal of 21121002253421 is 12435220012112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21121002253421 - 2⁶ = 21121002253357 is a prime.

It is a super-5 number, since 5×21121002253421⁵ (a number of 68 digits) contains 55555 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121002253321) 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, 1508643018095 + ... + 1508643018108.

It is an arithmetic number, because the mean of its divisors is an integer number (6034572072408).

Almost surely, 2^{21121002253421} is an apocalyptic number.

It is an amenable number.

21121002253421 is a deficient number, since it is larger than the sum of its proper divisors (3017286036211).

21121002253421 is an equidigital number, since it uses as much as digits as its factorization.

21121002253421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3017286036210.

The product of its (nonzero) digits is 1920, while the sum is 26.

Adding to 21121002253421 its reverse (12435220012112), we get a palindrome (33556222265533).

The spelling of 21121002253421 in words is "twenty-one trillion, one hundred twenty-one billion, two million, two hundred fifty-three thousand, four hundred twenty-one".