20308987 has 4 divisors (see below), whose sum is σ = 20518456. Its totient is φ = 20099520.

The previous prime is 20308969. The next prime is 20308991. The reversal of 20308987 is 78980302.

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 20308987 - 2⁷ = 20308859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20308907) 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, 104589 + ... + 104782.

It is an arithmetic number, because the mean of its divisors is an integer number (5129614).

Almost surely, 2^20308987 is an apocalyptic number.

20308987 is a deficient number, since it is larger than the sum of its proper divisors (209469).

20308987 is an equidigital number, since it uses as much as digits as its factorization.

20308987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209468.

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 20308987 is about 4506.5493451198. The cubic root of 20308987 is about 272.8324903684.

The spelling of 20308987 in words is "twenty million, three hundred eight thousand, nine hundred eighty-seven".