21040541553 has 4 divisors (see below), whose sum is σ = 28054055408. Its totient is φ = 14027027700.

The previous prime is 21040541539. The next prime is 21040541567. The reversal of 21040541553 is 35514504012.

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 an interprime number because it is at equal distance from previous prime (21040541539) and next prime (21040541567).

It is not a de Polignac number, because 21040541553 - 2²⁵ = 21006987121 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 21040541553.

It is not an unprimeable number, because it can be changed into a prime (21040541513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3506756923 + ... + 3506756928.

It is an arithmetic number, because the mean of its divisors is an integer number (7013513852).

Almost surely, 2^21040541553 is an apocalyptic number.

It is an amenable number.

21040541553 is a deficient number, since it is larger than the sum of its proper divisors (7013513855).

21040541553 is an equidigital number, since it uses as much as digits as its factorization.

21040541553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7013513854.

The product of its (nonzero) digits is 12000, while the sum is 30.

The spelling of 21040541553 in words is "twenty-one billion, forty million, five hundred forty-one thousand, five hundred fifty-three".