20551555 has 8 divisors (see below), whose sum is σ = 26112672. Its totient is φ = 15474048.

The previous prime is 20551523. The next prime is 20551561. The reversal of 20551555 is 55515502.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20551555 - 2⁵ = 20551523 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 120807 + ... + 120976.

It is an arithmetic number, because the mean of its divisors is an integer number (3264084).

Almost surely, 2^20551555 is an apocalyptic number.

20551555 is a deficient number, since it is larger than the sum of its proper divisors (5561117).

20551555 is a wasteful number, since it uses less digits than its factorization.

20551555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 241805.

The product of its (nonzero) digits is 6250, while the sum is 28.

The square root of 20551555 is about 4533.3822914023. The cubic root of 20551555 is about 273.9144199671.

The spelling of 20551555 in words is "twenty million, five hundred fifty-one thousand, five hundred fifty-five".