21251103213421 has 4 divisors (see below), whose sum is σ = 21520104520000. Its totient is φ = 20982101906844.

The previous prime is 21251103213413. The next prime is 21251103213427. The reversal of 21251103213421 is 12431230115212.

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 21251103213421 - 2³ = 21251103213413 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21251103213421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251103213427) 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, 134500653171 + ... + 134500653328.

It is an arithmetic number, because the mean of its divisors is an integer number (5380026130000).

Almost surely, 2^{21251103213421} is an apocalyptic number.

It is an amenable number.

21251103213421 is a deficient number, since it is larger than the sum of its proper divisors (269001306579).

21251103213421 is an equidigital number, since it uses as much as digits as its factorization.

21251103213421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 269001306578.

The product of its (nonzero) digits is 2880, while the sum is 28.

Adding to 21251103213421 its reverse (12431230115212), we get a palindrome (33682333328633).

The spelling of 21251103213421 in words is "twenty-one trillion, two hundred fifty-one billion, one hundred three million, two hundred thirteen thousand, four hundred twenty-one".