820001540 has 24 divisors (see below), whose sum is σ = 1738726080. Its totient is φ = 324815328.

The previous prime is 820001521. The next prime is 820001549. The reversal of 820001540 is 45100028.

It is a Harshad number since it is a multiple of its sum of digits (20).

820001540 is a modest number, since divided by 1540 gives 820 as remainder.

It is not an unprimeable number, because it can be changed into a prime (820001549) 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 7 ways as a sum of consecutive naturals, for example, 196970 + ... + 201089.

It is an arithmetic number, because the mean of its divisors is an integer number (72446920).

Almost surely, 2^820001540 is an apocalyptic number.

It is an amenable number.

820001540 is an abundant number, since it is smaller than the sum of its proper divisors (918724540).

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

820001540 is a wasteful number, since it uses less digits than its factorization.

820001540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398171 (or 398169 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 820001540 is about 28635.6690161065. The cubic root of 820001540 is about 935.9907482588.

Adding to 820001540 its reverse (45100028), we get a palindrome (865101568).

The spelling of 820001540 in words is "eight hundred twenty million, one thousand, five hundred forty".