20831887 has 4 divisors (see below), whose sum is σ = 20841480. Its totient is φ = 20822296.

The previous prime is 20831869. The next prime is 20831891. The reversal of 20831887 is 78813802.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20831887 - 2¹¹ = 20829839 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 (20831807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 189 + ... + 6457.

It is an arithmetic number, because the mean of its divisors is an integer number (5210370).

Almost surely, 2^20831887 is an apocalyptic number.

20831887 is a deficient number, since it is larger than the sum of its proper divisors (9593).

20831887 is an equidigital number, since it uses as much as digits as its factorization.

20831887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9592.

The product of its (nonzero) digits is 21504, while the sum is 37.

The square root of 20831887 is about 4564.1962052480. The cubic root of 20831887 is about 275.1542363439.

The spelling of 20831887 in words is "twenty million, eight hundred thirty-one thousand, eight hundred eighty-seven".