856721742 has 32 divisors (see below), whose sum is σ = 1811166720. Its totient is φ = 269412480.

The previous prime is 856721731. The next prime is 856721771. The reversal of 856721742 is 247127658.

It is a junction number, because it is equal to n+sod(n) for n = 856721694 and 856721703.

It is a congruent number.

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, 11883 + ... + 43065.

It is an arithmetic number, because the mean of its divisors is an integer number (56598960).

Almost surely, 2^856721742 is an apocalyptic number.

856721742 is an abundant number, since it is smaller than the sum of its proper divisors (954444978).

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

856721742 is a wasteful number, since it uses less digits than its factorization.

856721742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31448.

The product of its digits is 188160, while the sum is 42.

The square root of 856721742 is about 29269.8093946647. The cubic root of 856721742 is about 949.7586615025.

The spelling of 856721742 in words is "eight hundred fifty-six million, seven hundred twenty-one thousand, seven hundred forty-two".