21750709 has 16 divisors (see below), whose sum is σ = 23748480. Its totient is φ = 19863360.

The previous prime is 21750697. The next prime is 21750719. The reversal of 21750709 is 90705712.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21750709 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 (21750719) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51702 + ... + 52120.

It is an arithmetic number, because the mean of its divisors is an integer number (1484280).

Almost surely, 2^21750709 is an apocalyptic number.

It is an amenable number.

21750709 is a deficient number, since it is larger than the sum of its proper divisors (1997771).

21750709 is a wasteful number, since it uses less digits than its factorization.

21750709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 540.

The product of its (nonzero) digits is 4410, while the sum is 31.

The square root of 21750709 is about 4663.7655387037. The cubic root of 21750709 is about 279.1415416412.

The spelling of 21750709 in words is "twenty-one million, seven hundred fifty thousand, seven hundred nine".