77649978 has 64 divisors (see below), whose sum is σ = 191250432. Its totient is φ = 20528640.

The previous prime is 77649967. The next prime is 77649983. The reversal of 77649978 is 87994677.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28650 + ... + 31242.

It is an arithmetic number, because the mean of its divisors is an integer number (2988288).

Almost surely, 2^77649978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77649978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (95625216).

77649978 is an abundant number, since it is smaller than the sum of its proper divisors (113600454).

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

77649978 is a wasteful number, since it uses less digits than its factorization.

77649978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2659.

The product of its digits is 5334336, while the sum is 57.

The square root of 77649978 is about 8811.9224917154. The cubic root of 77649978 is about 426.6257967309.

The spelling of 77649978 in words is "seventy-seven million, six hundred forty-nine thousand, nine hundred seventy-eight".