21003869953 has 4 divisors (see below), whose sum is σ = 22913312688. Its totient is φ = 19094427220.

The previous prime is 21003869917. The next prime is 21003870077. The reversal of 21003869953 is 35996830012.

It is a happy number.

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 de Polignac number, because none of the positive numbers 2^k-21003869953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21003861953) 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, 954721351 + ... + 954721372.

It is an arithmetic number, because the mean of its divisors is an integer number (5728328172).

Almost surely, 2^21003869953 is an apocalyptic number.

It is an amenable number.

21003869953 is a deficient number, since it is larger than the sum of its proper divisors (1909442735).

21003869953 is a wasteful number, since it uses less digits than its factorization.

21003869953 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1909442734.

The product of its (nonzero) digits is 349920, while the sum is 46.

The spelling of 21003869953 in words is "twenty-one billion, three million, eight hundred sixty-nine thousand, nine hundred fifty-three".