77661816 has 64 divisors (see below), whose sum is σ = 209942400. Its totient is φ = 23856768.

The previous prime is 77661809. The next prime is 77661893. The reversal of 77661816 is 61816677.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14571 + ... + 19173.

It is an arithmetic number, because the mean of its divisors is an integer number (3280350).

Almost surely, 2^77661816 is an apocalyptic number.

77661816 is a gapful number since it is divisible by the number (76) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77661816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104971200).

77661816 is an abundant number, since it is smaller than the sum of its proper divisors (132280584).

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

77661816 is a wasteful number, since it uses less digits than its factorization.

77661816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4668 (or 4664 counting only the distinct ones).

The product of its digits is 84672, while the sum is 42.

The square root of 77661816 is about 8812.5941697096. The cubic root of 77661816 is about 426.6474758078.

The spelling of 77661816 in words is "seventy-seven million, six hundred sixty-one thousand, eight hundred sixteen".