20780287 has 4 divisors (see below), whose sum is σ = 22669416. Its totient is φ = 18891160.

The previous prime is 20780257. The next prime is 20780303. The reversal of 20780287 is 78208702.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20780287 - 2¹⁹ = 20255999 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20780237) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 944548 + ... + 944569.

It is an arithmetic number, because the mean of its divisors is an integer number (5667354).

Almost surely, 2^20780287 is an apocalyptic number.

20780287 is a deficient number, since it is larger than the sum of its proper divisors (1889129).

20780287 is a wasteful number, since it uses less digits than its factorization.

20780287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1889128.

The product of its (nonzero) digits is 12544, while the sum is 34.

The square root of 20780287 is about 4558.5400075024. The cubic root of 20780287 is about 274.9268654005.

Adding to 20780287 its reverse (78208702), we get a palindrome (98988989).

The spelling of 20780287 in words is "twenty million, seven hundred eighty thousand, two hundred eighty-seven".