856557720 has 128 divisors (see below), whose sum is σ = 2979417600. Its totient is φ = 218477952.

The previous prime is 856557707. The next prime is 856557727. The reversal of 856557720 is 27755658.

856557720 is a `hidden beast` number, since 8 + 56 + 5 + 577 + 20 = 666.

It is a super-2 number, since 2×856557720² = 1467382255383196800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (856557727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7599 + ... + 42081.

It is an arithmetic number, because the mean of its divisors is an integer number (23276700).

Almost surely, 2^856557720 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 856557720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1489708800).

856557720 is an abundant number, since it is smaller than the sum of its proper divisors (2122859880).

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

856557720 is a wasteful number, since it uses less digits than its factorization.

856557720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34526 (or 34516 counting only the distinct ones).

The product of its (nonzero) digits is 588000, while the sum is 45.

The square root of 856557720 is about 29267.0073632410. The cubic root of 856557720 is about 949.6980462329.

The spelling of 856557720 in words is "eight hundred fifty-six million, five hundred fifty-seven thousand, seven hundred twenty".