20505551659 has 4 divisors (see below), whose sum is σ = 21584791240. Its totient is φ = 19426312080.

The previous prime is 20505551641. The next prime is 20505551669. The reversal of 20505551659 is 95615550502.

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 20505551659 - 2³¹ = 18358068011 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20505551669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 539619762 + ... + 539619799.

It is an arithmetic number, because the mean of its divisors is an integer number (5396197810).

Almost surely, 2^20505551659 is an apocalyptic number.

20505551659 is a deficient number, since it is larger than the sum of its proper divisors (1079239581).

20505551659 is a wasteful number, since it uses less digits than its factorization.

20505551659 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1079239580.

The product of its (nonzero) digits is 337500, while the sum is 43.

The spelling of 20505551659 in words is "twenty billion, five hundred five million, five hundred fifty-one thousand, six hundred fifty-nine".