820899540 has 108 divisors (see below), whose sum is σ = 2553217212. Its totient is φ = 213488640.

The previous prime is 820899539. The next prime is 820899637. The reversal of 820899540 is 45998028.

820899540 is a `hidden beast` number, since 8 + 20 + 89 + 9 + 540 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 71673156 + 749226384 = 8466^2 + 27372^2 .

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 301224 + ... + 303936.

Almost surely, 2^820899540 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 820899540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1276608606).

820899540 is an abundant number, since it is smaller than the sum of its proper divisors (1732317672).

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

820899540 is a wasteful number, since it uses less digits than its factorization.

820899540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2810 (or 2764 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 45.

The square root of 820899540 is about 28651.3444710715. The cubic root of 820899540 is about 936.3322976398.

The spelling of 820899540 in words is "eight hundred twenty million, eight hundred ninety-nine thousand, five hundred forty".