20156642856 has 128 divisors (see below), whose sum is σ = 64137216000. Its totient is φ = 5745733056.

The previous prime is 20156642809. The next prime is 20156642881. The reversal of 20156642856 is 65824665102.

20156642856 is a `hidden beast` number, since 2 + 0 + 1 + 566 + 4 + 2 + 85 + 6 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 648585 + ... + 678951.

It is an arithmetic number, because the mean of its divisors is an integer number (501072000).

Almost surely, 2^20156642856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20156642856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32068608000).

20156642856 is an abundant number, since it is smaller than the sum of its proper divisors (43980573144).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20156642856 is a wasteful number, since it uses less digits than its factorization.

20156642856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30828 (or 30818 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 45.

The spelling of 20156642856 in words is "twenty billion, one hundred fifty-six million, six hundred forty-two thousand, eight hundred fifty-six".