1389457778 has 4 divisors (see below), whose sum is σ = 2084186670. Its totient is φ = 694728888.

The previous prime is 1389457777. The next prime is 1389457793. The reversal of 1389457778 is 8777549831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8777549831 = 39619 ⋅221549.

It can be written as a sum of positive squares in only one way, i.e., 971132569 + 418325209 = 31163^2 + 20453^2 .

It is a super-3 number, since 3×1389457778³ (a number of 28 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (1389457777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 347364443 + ... + 347364446.

Almost surely, 2^1389457778 is an apocalyptic number.

1389457778 is a deficient number, since it is larger than the sum of its proper divisors (694728892).

1389457778 is an equidigital number, since it uses as much as digits as its factorization.

1389457778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 694728891.

The product of its digits is 11854080, while the sum is 59.

The square root of 1389457778 is about 37275.4312919381. The cubic root of 1389457778 is about 1115.8738959228.

The spelling of 1389457778 in words is "one billion, three hundred eighty-nine million, four hundred fifty-seven thousand, seven hundred seventy-eight".