20840287 has 12 divisors (see below), whose sum is σ = 23086056. Its totient is φ = 18701280.

The previous prime is 20840269. The next prime is 20840293. The reversal of 20840287 is 78204802.

It is not a de Polignac number, because 20840287 - 2²³ = 12451679 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20840297) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17212 + ... + 18382.

It is an arithmetic number, because the mean of its divisors is an integer number (1923838).

Almost surely, 2^20840287 is an apocalyptic number.

20840287 is a deficient number, since it is larger than the sum of its proper divisors (2245769).

20840287 is a wasteful number, since it uses less digits than its factorization.

20840287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1258 (or 1221 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 31.

The square root of 20840287 is about 4565.1163183428. The cubic root of 20840287 is about 275.1912146710.

The spelling of 20840287 in words is "twenty million, eight hundred forty thousand, two hundred eighty-seven".