821851434 has 80 divisors (see below), whose sum is σ = 1957142088. Its totient is φ = 256877568.

The previous prime is 821851409. The next prime is 821851463. The reversal of 821851434 is 434158128.

821851434 is a `hidden beast` number, since 8 + 218 + 5 + 1 + 434 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 795070809 + 26780625 = 28197^2 + 5175^2 .

It is a super-3 number, since 3×821851434³ (a number of 28 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 1258252 + ... + 1258904.

Almost surely, 2^821851434 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821851434, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (978571044).

821851434 is an abundant number, since it is smaller than the sum of its proper divisors (1135290654).

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

821851434 is a wasteful number, since it uses less digits than its factorization.

821851434 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1141 (or 1132 counting only the distinct ones).

The product of its digits is 30720, while the sum is 36.

The square root of 821851434 is about 28667.9513394313. The cubic root of 821851434 is about 936.6940734598.

The spelling of 821851434 in words is "eight hundred twenty-one million, eight hundred fifty-one thousand, four hundred thirty-four".