20561575556 has 48 divisors (see below), whose sum is σ = 36784480320. Its totient is φ = 10055011200.

The previous prime is 20561575547. The next prime is 20561575589. The reversal of 20561575556 is 65557516502.

It is a self number, because there is not a number n which added to its sum of digits gives 20561575556.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12746606 + ... + 12748218.

It is an arithmetic number, because the mean of its divisors is an integer number (766343340).

Almost surely, 2^20561575556 is an apocalyptic number.

It is an amenable number.

20561575556 is a deficient number, since it is larger than the sum of its proper divisors (16222904764).

20561575556 is a wasteful number, since it uses less digits than its factorization.

20561575556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2084 (or 2082 counting only the distinct ones).

The product of its (nonzero) digits is 1575000, while the sum is 47.

The spelling of 20561575556 in words is "twenty billion, five hundred sixty-one million, five hundred seventy-five thousand, five hundred fifty-six".