21240520553 has 4 divisors (see below), whose sum is σ = 24274880640. Its totient is φ = 18206160468.

The previous prime is 21240520537. The next prime is 21240520559. The reversal of 21240520553 is 35502504212.

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 21240520553 - 2⁴ = 21240520537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21240520559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1517180033 + ... + 1517180046.

It is an arithmetic number, because the mean of its divisors is an integer number (6068720160).

Almost surely, 2^21240520553 is an apocalyptic number.

It is an amenable number.

21240520553 is a deficient number, since it is larger than the sum of its proper divisors (3034360087).

21240520553 is an equidigital number, since it uses as much as digits as its factorization.

21240520553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3034360086.

The product of its (nonzero) digits is 12000, while the sum is 29.

The spelling of 21240520553 in words is "twenty-one billion, two hundred forty million, five hundred twenty thousand, five hundred fifty-three".