20778287 has 2 divisors, whose sum is σ = 20778288. Its totient is φ = 20778286.

The previous prime is 20778283. The next prime is 20778299. The reversal of 20778287 is 78287702.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20778287 - 2² = 20778283 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20778283) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10389143 + 10389144.

It is an arithmetic number, because the mean of its divisors is an integer number (10389144).

Almost surely, 2^20778287 is an apocalyptic number.

20778287 is a deficient number, since it is larger than the sum of its proper divisors (1).

20778287 is an equidigital number, since it uses as much as digits as its factorization.

20778287 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 87808, while the sum is 41.

The square root of 20778287 is about 4558.3206337422. The cubic root of 20778287 is about 274.9180449998.

The spelling of 20778287 in words is "twenty million, seven hundred seventy-eight thousand, two hundred eighty-seven".