820138387 has 4 divisors (see below), whose sum is σ = 846594496. Its totient is φ = 793682280.

The previous prime is 820138379. The next prime is 820138399. The reversal of 820138387 is 783831028.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 820138387 - 2³ = 820138379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (820138087) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13228008 + ... + 13228069.

It is an arithmetic number, because the mean of its divisors is an integer number (211648624).

Almost surely, 2^820138387 is an apocalyptic number.

820138387 is a deficient number, since it is larger than the sum of its proper divisors (26456109).

820138387 is a wasteful number, since it uses less digits than its factorization.

820138387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26456108.

The product of its (nonzero) digits is 64512, while the sum is 40.

The square root of 820138387 is about 28638.0583664466. The cubic root of 820138387 is about 936.0428133648.

The spelling of 820138387 in words is "eight hundred twenty million, one hundred thirty-eight thousand, three hundred eighty-seven".