20278649 has 2 divisors, whose sum is σ = 20278650. Its totient is φ = 20278648.

The previous prime is 20278631. The next prime is 20278651. The reversal of 20278649 is 94687202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15460624 + 4818025 = 3932^2 + 2195^2 .

It is a cyclic number.

It is not a de Polignac number, because 20278649 - 2⁸ = 20278393 is a prime.

It is a super-2 number, since 2×20278649² = 822447210530402, which contains 22 as substring.

Together with 20278651, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20278549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10139324 + 10139325.

It is an arithmetic number, because the mean of its divisors is an integer number (10139325).

Almost surely, 2^20278649 is an apocalyptic number.

It is an amenable number.

20278649 is a deficient number, since it is larger than the sum of its proper divisors (1).

20278649 is an equidigital number, since it uses as much as digits as its factorization.

20278649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48384, while the sum is 38.

The square root of 20278649 is about 4503.1820971398. The cubic root of 20278649 is about 272.6965683245.

The spelling of 20278649 in words is "twenty million, two hundred seventy-eight thousand, six hundred forty-nine".