20856644874 has 96 divisors (see below), whose sum is σ = 49401031680. Its totient is φ = 6320916864.

The previous prime is 20856644873. The next prime is 20856644903. The reversal of 20856644874 is 47844665802.

It is a happy number.

20856644874 is a `hidden beast` number, since 2 + 0 + 8 + 566 + 4 + 4 + 8 + 74 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 20856644874.

It is not an unprimeable number, because it can be changed into a prime (20856644873) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 7242967 + ... + 7245845.

It is an arithmetic number, because the mean of its divisors is an integer number (514594080).

Almost surely, 2^20856644874 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20856644874, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24700515840).

20856644874 is an abundant number, since it is smaller than the sum of its proper divisors (28544386806).

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

20856644874 is a wasteful number, since it uses less digits than its factorization.

20856644874 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3356 (or 3353 counting only the distinct ones).

The product of its (nonzero) digits is 10321920, while the sum is 54.

The spelling of 20856644874 in words is "twenty billion, eight hundred fifty-six million, six hundred forty-four thousand, eight hundred seventy-four".