20556511531 has 8 divisors (see below), whose sum is σ = 20625056064. Its totient is φ = 20488035840.

The previous prime is 20556511529. The next prime is 20556511561. The reversal of 20556511531 is 13511565502.

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 20556511531 - 2¹ = 20556511529 is a prime.

It is a super-2 number, since 2×20556511531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20556511561) 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 7 ways as a sum of consecutive naturals, for example, 619851 + ... + 652171.

It is an arithmetic number, because the mean of its divisors is an integer number (2578132008).

Almost surely, 2^20556511531 is an apocalyptic number.

20556511531 is a deficient number, since it is larger than the sum of its proper divisors (68544533).

20556511531 is a wasteful number, since it uses less digits than its factorization.

20556511531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34421.

The product of its (nonzero) digits is 22500, while the sum is 34.

The spelling of 20556511531 in words is "twenty billion, five hundred fifty-six million, five hundred eleven thousand, five hundred thirty-one".