20555987 has 4 divisors (see below), whose sum is σ = 20569536. Its totient is φ = 20542440.

The previous prime is 20555971. The next prime is 20555999. The reversal of 20555987 is 78955502.

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 20555987 - 2⁴ = 20555971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20555947) 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 3 ways as a sum of consecutive naturals, for example, 4163 + ... + 7644.

It is an arithmetic number, because the mean of its divisors is an integer number (5142384).

Almost surely, 2^20555987 is an apocalyptic number.

20555987 is a deficient number, since it is larger than the sum of its proper divisors (13549).

20555987 is a wasteful number, since it uses less digits than its factorization.

20555987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13548.

The product of its (nonzero) digits is 126000, while the sum is 41.

The square root of 20555987 is about 4533.8710833018. The cubic root of 20555987 is about 273.9341086874.

The spelling of 20555987 in words is "twenty million, five hundred fifty-five thousand, nine hundred eighty-seven".