21210379709 has 4 divisors (see below), whose sum is σ = 21211756416. Its totient is φ = 21209003004.

The previous prime is 21210379691. The next prime is 21210379717. The reversal of 21210379709 is 90797301212.

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 21210379709 - 2²⁸ = 20941944253 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 (21210379739) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 664979 + ... + 696144.

It is an arithmetic number, because the mean of its divisors is an integer number (5302939104).

Almost surely, 2^21210379709 is an apocalyptic number.

It is an amenable number.

21210379709 is a deficient number, since it is larger than the sum of its proper divisors (1376707).

21210379709 is a wasteful number, since it uses less digits than its factorization.

21210379709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1376706.

The product of its (nonzero) digits is 47628, while the sum is 41.

The spelling of 21210379709 in words is "twenty-one billion, two hundred ten million, three hundred seventy-nine thousand, seven hundred nine".