21010505421 has 8 divisors (see below), whose sum is σ = 28055026080. Its totient is φ = 13986494192.

The previous prime is 21010505413. The next prime is 21010505437. The reversal of 21010505421 is 12450501012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21010505421 - 2³ = 21010505413 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010505441) 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 7 ways as a sum of consecutive naturals, for example, 5124966 + ... + 5129063.

It is an arithmetic number, because the mean of its divisors is an integer number (3506878260).

Almost surely, 2^21010505421 is an apocalyptic number.

It is an amenable number.

21010505421 is a deficient number, since it is larger than the sum of its proper divisors (7044520659).

21010505421 is a wasteful number, since it uses less digits than its factorization.

21010505421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10254715.

The product of its (nonzero) digits is 400, while the sum is 21.

The spelling of 21010505421 in words is "twenty-one billion, ten million, five hundred five thousand, four hundred twenty-one".