21310421 has 4 divisors (see below), whose sum is σ = 23247744. Its totient is φ = 19373100.

The previous prime is 21310417. The next prime is 21310433. The reversal of 21310421 is 12401312.

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 21310421 - 2² = 21310417 is a prime.

It is a super-3 number, since 3×21310421³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21310396 and 21310405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21310451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 968645 + ... + 968666.

It is an arithmetic number, because the mean of its divisors is an integer number (5811936).

Almost surely, 2^21310421 is an apocalyptic number.

It is an amenable number.

21310421 is a deficient number, since it is larger than the sum of its proper divisors (1937323).

21310421 is a wasteful number, since it uses less digits than its factorization.

21310421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1937322.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21310421 is about 4616.3211543392. The cubic root of 21310421 is about 277.2451833934.

Adding to 21310421 its reverse (12401312), we get a palindrome (33711733).

The spelling of 21310421 in words is "twenty-one million, three hundred ten thousand, four hundred twenty-one".