20987875 has 16 divisors (see below), whose sum is σ = 27574560. Its totient is φ = 15904800.

The previous prime is 20987873. The next prime is 20987881. The reversal of 20987875 is 57878902.

It is not a de Polignac number, because 20987875 - 2¹ = 20987873 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20987873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2044 + ... + 6793.

It is an arithmetic number, because the mean of its divisors is an integer number (1723410).

Almost surely, 2^20987875 is an apocalyptic number.

20987875 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

20987875 is a deficient number, since it is larger than the sum of its proper divisors (6586685).

20987875 is an equidigital number, since it uses as much as digits as its factorization.

20987875 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8871 (or 8861 counting only the distinct ones).

The product of its (nonzero) digits is 282240, while the sum is 46.

The square root of 20987875 is about 4581.2525579802. The cubic root of 20987875 is about 275.8393090732.

The spelling of 20987875 in words is "twenty million, nine hundred eighty-seven thousand, eight hundred seventy-five".