20779709 has 4 divisors (see below), whose sum is σ = 20855004. Its totient is φ = 20704416.

The previous prime is 20779697. The next prime is 20779723. The reversal of 20779709 is 90797702.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4214809 + 16564900 = 2053^2 + 4070^2 .

It is a cyclic number.

It is not a de Polignac number, because 20779709 - 2¹² = 20775613 is a prime.

It is a super-2 number, since 2×20779709² = 863592612249362, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20779739) 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, 37232 + ... + 37785.

It is an arithmetic number, because the mean of its divisors is an integer number (5213751).

Almost surely, 2^20779709 is an apocalyptic number.

It is an amenable number.

20779709 is a deficient number, since it is larger than the sum of its proper divisors (75295).

20779709 is an equidigital number, since it uses as much as digits as its factorization.

20779709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75294.

The product of its (nonzero) digits is 55566, while the sum is 41.

The square root of 20779709 is about 4558.4766095704. The cubic root of 20779709 is about 274.9243163629.

The spelling of 20779709 in words is "twenty million, seven hundred seventy-nine thousand, seven hundred nine".