77997556 has 72 divisors (see below), whose sum is σ = 172658304. Its totient is φ = 30176640.

The previous prime is 77997551. The next prime is 77997583. The reversal of 77997556 is 65579977.

It is a junction number, because it is equal to n+sod(n) for n = 77997497 and 77997506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77997551) 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 23 ways as a sum of consecutive naturals, for example, 250641 + ... + 250951.

It is an arithmetic number, because the mean of its divisors is an integer number (2398032).

Almost surely, 2^77997556 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77997556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (86329152).

77997556 is an abundant number, since it is smaller than the sum of its proper divisors (94660748).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

77997556 is a wasteful number, since it uses less digits than its factorization.

77997556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401 (or 386 counting only the distinct ones).

The product of its digits is 4167450, while the sum is 55.

The square root of 77997556 is about 8831.6225009904. The cubic root of 77997556 is about 427.2614055686.

The spelling of 77997556 in words is "seventy-seven million, nine hundred ninety-seven thousand, five hundred fifty-six".