1028378821 has 4 divisors (see below), whose sum is σ = 1030113612. Its totient is φ = 1026644032.

The previous prime is 1028378803. The next prime is 1028378833. The reversal of 1028378821 is 1288738201.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1288738201 = 35899².

It can be written as a sum of positive squares in 2 ways, for example, as 822886596 + 205492225 = 28686^2 + 14335^2 .

It is a cyclic number.

It is not a de Polignac number, because 1028378821 - 2⁵ = 1028378789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1028376821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 866506 + ... + 867691.

It is an arithmetic number, because the mean of its divisors is an integer number (257528403).

Almost surely, 2^1028378821 is an apocalyptic number.

It is an amenable number.

1028378821 is a deficient number, since it is larger than the sum of its proper divisors (1734791).

1028378821 is an equidigital number, since it uses as much as digits as its factorization.

1028378821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1734790.

The product of its (nonzero) digits is 43008, while the sum is 40.

The square root of 1028378821 is about 32068.3460908105. The cubic root of 1028378821 is about 1009.3715074959.

The spelling of 1028378821 in words is "one billion, twenty-eight million, three hundred seventy-eight thousand, eight hundred twenty-one".