1328386781 has 4 divisors (see below), whose sum is σ = 1386142752. Its totient is φ = 1270630812.

The previous prime is 1328386771. The next prime is 1328386811. The reversal of 1328386781 is 1876838231.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1328386781 - 2²² = 1324192477 is a prime.

It is a super-2 number, since 2×1328386781² = 3529222879871083922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1328386751) 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, 28877951 + ... + 28877996.

It is an arithmetic number, because the mean of its divisors is an integer number (346535688).

Almost surely, 2^1328386781 is an apocalyptic number.

It is an amenable number.

1328386781 is a deficient number, since it is larger than the sum of its proper divisors (57755971).

1328386781 is an equidigital number, since it uses as much as digits as its factorization.

1328386781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57755970.

The product of its digits is 387072, while the sum is 47.

The square root of 1328386781 is about 36447.0407715085. The cubic root of 1328386781 is about 1099.2796333088.

The spelling of 1328386781 in words is "one billion, three hundred twenty-eight million, three hundred eighty-six thousand, seven hundred eighty-one".