21310553 has 4 divisors (see below), whose sum is σ = 23247888. Its totient is φ = 19373220.

The previous prime is 21310519. The next prime is 21310561. The reversal of 21310553 is 35501312.

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 21310553 - 2⁸ = 21310297 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21310253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 968651 + ... + 968672.

It is an arithmetic number, because the mean of its divisors is an integer number (5811972).

Almost surely, 2^21310553 is an apocalyptic number.

It is an amenable number.

21310553 is a deficient number, since it is larger than the sum of its proper divisors (1937335).

21310553 is a wasteful number, since it uses less digits than its factorization.

21310553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1937334.

The product of its (nonzero) digits is 450, while the sum is 20.

The square root of 21310553 is about 4616.3354514160. The cubic root of 21310553 is about 277.2457558252.

Adding to 21310553 its reverse (35501312), we get a palindrome (56811865).

The spelling of 21310553 in words is "twenty-one million, three hundred ten thousand, five hundred fifty-three".