77781951 has 20 divisors (see below), whose sum is σ = 125132392. Its totient is φ = 47865168.

The previous prime is 77781937. The next prime is 77781971. The reversal of 77781951 is 15918777.

It is a happy number.

It is not a de Polignac number, because 77781951 - 2¹¹ = 77779903 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 77781897 and 77781906.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77781931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 35881 + ... + 37986.

Almost surely, 2^77781951 is an apocalyptic number.

77781951 is a deficient number, since it is larger than the sum of its proper divisors (47350441).

77781951 is a wasteful number, since it uses less digits than its factorization.

77781951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73892 (or 73883 counting only the distinct ones).

The product of its digits is 123480, while the sum is 45.

The square root of 77781951 is about 8819.4076331690. The cubic root of 77781951 is about 426.8673560137.

It can be divided in two parts, 777 and 81951, that added together give a palindrome (82728).

The spelling of 77781951 in words is "seventy-seven million, seven hundred eighty-one thousand, nine hundred fifty-one".