77825791 has 4 divisors (see below), whose sum is σ = 77859184. Its totient is φ = 77792400.

The previous prime is 77825789. The next prime is 77825827. The reversal of 77825791 is 19752877.

It is a semiprime because it is the product of two primes.

It is a 4-Lehmer number, since φ(77825791) divides (77825791-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 77825791 - 2¹ = 77825789 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 (77825731) 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, 12915 + ... + 17956.

It is an arithmetic number, because the mean of its divisors is an integer number (19464796).

Almost surely, 2^77825791 is an apocalyptic number.

77825791 is the 4716-th centered heptagonal number.

77825791 is a deficient number, since it is larger than the sum of its proper divisors (33393).

77825791 is a wasteful number, since it uses less digits than its factorization.

77825791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33392.

The product of its digits is 246960, while the sum is 46.

The square root of 77825791 is about 8821.8927107509. The cubic root of 77825791 is about 426.9475389262.

It can be divided in two parts, 778 and 25791, that added together give a square (26569 = 163²).

The spelling of 77825791 in words is "seventy-seven million, eight hundred twenty-five thousand, seven hundred ninety-one".