7771991 has 4 divisors (see below), whose sum is σ = 7794000. Its totient is φ = 7749984.

The previous prime is 7771963. The next prime is 7771993. The reversal of 7771991 is 1991777.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1991777 = 23 ⋅86599.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7771991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7771993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10466 + ... + 11183.

It is an arithmetic number, because the mean of its divisors is an integer number (1948500).

Almost surely, 2^7771991 is an apocalyptic number.

7771991 is a deficient number, since it is larger than the sum of its proper divisors (22009).

7771991 is a wasteful number, since it uses less digits than its factorization.

7771991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22008.

The product of its digits is 27783, while the sum is 41.

The square root of 7771991 is about 2787.8290837137. The cubic root of 7771991 is about 198.0815822025.

The spelling of 7771991 in words is "seven million, seven hundred seventy-one thousand, nine hundred ninety-one".