1645381778 has 8 divisors (see below), whose sum is σ = 2468284272. Its totient is φ = 822620356.

The previous prime is 1645381769. The next prime is 1645381807. The reversal of 1645381778 is 8771835461.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1601 + ... + 57387.

It is an arithmetic number, because the mean of its divisors is an integer number (308535534).

Almost surely, 2^1645381778 is an apocalyptic number.

1645381778 is a deficient number, since it is larger than the sum of its proper divisors (822902494).

1645381778 is a wasteful number, since it uses less digits than its factorization.

1645381778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70536.

The product of its digits is 1128960, while the sum is 50.

The square root of 1645381778 is about 40563.3058070961. The cubic root of 1645381778 is about 1180.5622567061.

The spelling of 1645381778 in words is "one billion, six hundred forty-five million, three hundred eighty-one thousand, seven hundred seventy-eight".