21710635021 has 4 divisors (see below), whose sum is σ = 21710930044. Its totient is φ = 21710340000.

The previous prime is 21710635013. The next prime is 21710635031. The reversal of 21710635021 is 12053601712.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 15467896900 + 6242738121 = 124370^2 + 79011^2 .

It is a cyclic number.

It is not a de Polignac number, because 21710635021 - 2³ = 21710635013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21710635031) 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, 63271 + ... + 217771.

It is an arithmetic number, because the mean of its divisors is an integer number (5427732511).

Almost surely, 2^21710635021 is an apocalyptic number.

It is an amenable number.

21710635021 is a deficient number, since it is larger than the sum of its proper divisors (295023).

21710635021 is a wasteful number, since it uses less digits than its factorization.

21710635021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295022.

The product of its (nonzero) digits is 2520, while the sum is 28.

The spelling of 21710635021 in words is "twenty-one billion, seven hundred ten million, six hundred thirty-five thousand, twenty-one".