20278129 has 2 divisors, whose sum is σ = 20278130. Its totient is φ = 20278128.

The previous prime is 20278121. The next prime is 20278147. The reversal of 20278129 is 92187202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20007729 + 270400 = 4473^2 + 520^2 .

It is a cyclic number.

It is not a de Polignac number, because 20278129 - 2³ = 20278121 is a prime.

It is a super-2 number, since 2×20278129² = 822405031481282, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20278129.

It is not a weakly prime, because it can be changed into another prime (20278121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10139064 + 10139065.

It is an arithmetic number, because the mean of its divisors is an integer number (10139065).

Almost surely, 2^20278129 is an apocalyptic number.

It is an amenable number.

20278129 is a deficient number, since it is larger than the sum of its proper divisors (1).

20278129 is an equidigital number, since it uses as much as digits as its factorization.

20278129 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 20278129 is about 4503.1243598195. The cubic root of 20278129 is about 272.6942374094.

The spelling of 20278129 in words is "twenty million, two hundred seventy-eight thousand, one hundred twenty-nine".