6397778891 has 16 divisors (see below), whose sum is σ = 7512672960. Its totient is φ = 5333247360.

The previous prime is 6397778869. The next prime is 6397778903. The reversal of 6397778891 is 1988777936.

It is a de Polignac number, because none of the positive numbers 2^k-6397778891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6397778801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 830405 + ... + 838073.

It is an arithmetic number, because the mean of its divisors is an integer number (469542060).

Almost surely, 2^6397778891 is an apocalyptic number.

6397778891 is a deficient number, since it is larger than the sum of its proper divisors (1114894069).

6397778891 is a wasteful number, since it uses less digits than its factorization.

6397778891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10934.

The product of its digits is 32006016, while the sum is 65.

The square root of 6397778891 is about 79986.1168641159. The cubic root of 6397778891 is about 1856.4207278703.

The spelling of 6397778891 in words is "six billion, three hundred ninety-seven million, seven hundred seventy-eight thousand, eight hundred ninety-one".