1642128778 has 8 divisors (see below), whose sum is σ = 2465513568. Its totient is φ = 820290924.

The previous prime is 1642128767. The next prime is 1642128781. The reversal of 1642128778 is 8778212461.

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, 384076 + ... + 388327.

It is an arithmetic number, because the mean of its divisors is an integer number (308189196).

Almost surely, 2^1642128778 is an apocalyptic number.

1642128778 is a deficient number, since it is larger than the sum of its proper divisors (823384790).

1642128778 is a wasteful number, since it uses less digits than its factorization.

1642128778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 773468.

The product of its digits is 301056, while the sum is 46.

The square root of 1642128778 is about 40523.1881519705. The cubic root of 1642128778 is about 1179.7837337069.

The spelling of 1642128778 in words is "one billion, six hundred forty-two million, one hundred twenty-eight thousand, seven hundred seventy-eight".