77989891 has 8 divisors (see below), whose sum is σ = 89580800. Its totient is φ = 66511368.

The previous prime is 77989883. The next prime is 77989909. The reversal of 77989891 is 19898977.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 77989891 - 2³ = 77989883 is a prime.

It is a super-3 number, since 3×77989891³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77989801) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26601 + ... + 29386.

It is an arithmetic number, because the mean of its divisors is an integer number (11197600).

Almost surely, 2^77989891 is an apocalyptic number.

77989891 is a deficient number, since it is larger than the sum of its proper divisors (11590909).

77989891 is a wasteful number, since it uses less digits than its factorization.

77989891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56193.

The product of its digits is 2286144, while the sum is 58.

The square root of 77989891 is about 8831.1885383565. The cubic root of 77989891 is about 427.2474091216.

It can be divided in two parts, 7798 and 9891, that added together give a square (17689 = 133²).

The spelling of 77989891 in words is "seventy-seven million, nine hundred eighty-nine thousand, eight hundred ninety-one".