851866640 has 80 divisors (see below), whose sum is σ = 2076617088. Its totient is φ = 324369408.

The previous prime is 851866627. The next prime is 851866661. The reversal of 851866640 is 46668158.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 851866591 and 851866600.

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, 427727 + ... + 429713.

Almost surely, 2^851866640 is an apocalyptic number.

851866640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 851866640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1038308544).

851866640 is an abundant number, since it is smaller than the sum of its proper divisors (1224750448).

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

851866640 is a wasteful number, since it uses less digits than its factorization.

851866640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2256 (or 2250 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 44.

The square root of 851866640 is about 29186.7545300946. The cubic root of 851866640 is about 947.9611454222.

The spelling of 851866640 in words is "eight hundred fifty-one million, eight hundred sixty-six thousand, six hundred forty".