20279561 has 2 divisors, whose sum is σ = 20279562. Its totient is φ = 20279560.

The previous prime is 20279557. The next prime is 20279569. The reversal of 20279561 is 16597202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13097161 + 7182400 = 3619^2 + 2680^2 .

It is a cyclic number.

It is not a de Polignac number, because 20279561 - 2² = 20279557 is a prime.

It is a super-2 number, since 2×20279561² = 822521188705442, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20279569) 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, 10139780 + 10139781.

It is an arithmetic number, because the mean of its divisors is an integer number (10139781).

Almost surely, 2^20279561 is an apocalyptic number.

It is an amenable number.

20279561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20279561 is an equidigital number, since it uses as much as digits as its factorization.

20279561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7560, while the sum is 32.

The square root of 20279561 is about 4503.2833577291. The cubic root of 20279561 is about 272.7006562947.

The spelling of 20279561 in words is "twenty million, two hundred seventy-nine thousand, five hundred sixty-one".