77561903 has 4 divisors (see below), whose sum is σ = 77579640. Its totient is φ = 77544168.

The previous prime is 77561851. The next prime is 77561909. The reversal of 77561903 is 30916577.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 30916577 = 23 ⋅1344199.

It is a cyclic number.

It is not a de Polignac number, because 77561903 - 2²⁶ = 10453039 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 (77561909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2876 + ... + 12782.

It is an arithmetic number, because the mean of its divisors is an integer number (19394910).

Almost surely, 2^77561903 is an apocalyptic number.

77561903 is a deficient number, since it is larger than the sum of its proper divisors (17737).

77561903 is an equidigital number, since it uses as much as digits as its factorization.

77561903 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17736.

The product of its (nonzero) digits is 39690, while the sum is 38.

The square root of 77561903 is about 8806.9235831816. The cubic root of 77561903 is about 426.4644346650.

The spelling of 77561903 in words is "seventy-seven million, five hundred sixty-one thousand, nine hundred three".