1642377778 has 4 divisors (see below), whose sum is σ = 2463566670. Its totient is φ = 821188888.

The previous prime is 1642377743. The next prime is 1642377811. The reversal of 1642377778 is 8777732461.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8777732461 = 19 ⋅461985919.

It can be written as a sum of positive squares in only one way, i.e., 867479209 + 774898569 = 29453^2 + 27837^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410594443 + ... + 410594446.

Almost surely, 2^1642377778 is an apocalyptic number.

1642377778 is a deficient number, since it is larger than the sum of its proper divisors (821188892).

1642377778 is an equidigital number, since it uses as much as digits as its factorization.

1642377778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 821188891.

The product of its digits is 2765952, while the sum is 52.

The square root of 1642377778 is about 40526.2603505431. The cubic root of 1642377778 is about 1179.8433618568.

The spelling of 1642377778 in words is "one billion, six hundred forty-two million, three hundred seventy-seven thousand, seven hundred seventy-eight".