20279309 has 2 divisors, whose sum is σ = 20279310. Its totient is φ = 20279308.

The previous prime is 20279291. The next prime is 20279321. The reversal of 20279309 is 90397202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19758025 + 521284 = 4445^2 + 722^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20279309 is a prime.

It is a super-2 number, since 2×20279309² = 822500747034962, which contains 22 as substring.

It is equal to p_1287185 and since 20279309 and 1287185 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20279339) 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 as a sum of consecutive naturals, namely, 10139654 + 10139655.

It is an arithmetic number, because the mean of its divisors is an integer number (10139655).

Almost surely, 2^20279309 is an apocalyptic number.

It is an amenable number.

20279309 is a deficient number, since it is larger than the sum of its proper divisors (1).

20279309 is an equidigital number, since it uses as much as digits as its factorization.

20279309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6804, while the sum is 32.

The square root of 20279309 is about 4503.2553780571. The cubic root of 20279309 is about 272.6995267363.

The spelling of 20279309 in words is "twenty million, two hundred seventy-nine thousand, three hundred nine".