21130709 has 4 divisors (see below), whose sum is σ = 21194880. Its totient is φ = 21066540.

The previous prime is 21130699. The next prime is 21130727. The reversal of 21130709 is 90703112.

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 21130709 - 2⁸ = 21130453 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 (21130409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31589 + ... + 32250.

It is an arithmetic number, because the mean of its divisors is an integer number (5298720).

Almost surely, 2^21130709 is an apocalyptic number.

It is an amenable number.

21130709 is a deficient number, since it is larger than the sum of its proper divisors (64171).

21130709 is an equidigital number, since it uses as much as digits as its factorization.

21130709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64170.

The product of its (nonzero) digits is 378, while the sum is 23.

The square root of 21130709 is about 4596.8150930835. The cubic root of 21130709 is about 276.4636408279.

The spelling of 21130709 in words is "twenty-one million, one hundred thirty thousand, seven hundred nine".