77281680 has 160 divisors (see below), whose sum is σ = 276482304. Its totient is φ = 17491968.

The previous prime is 77281661. The next prime is 77281691. The reversal of 77281680 is 8618277.

It is a Cunningham number, because it is equal to 8791²-1.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 263614 + ... + 263906.

Almost surely, 2^77281680 is an apocalyptic number.

77281680 is a gapful number since it is divisible by the number (70) 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 77281680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (138241152).

77281680 is an abundant number, since it is smaller than the sum of its proper divisors (199200624).

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

77281680 is a wasteful number, since it uses less digits than its factorization.

77281680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 473 (or 467 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 39.

The square root of 77281680 is about 8790.9999431236. Note that the first 4 decimals coincide. The cubic root of 77281680 is about 425.9502245178.

The spelling of 77281680 in words is "seventy-seven million, two hundred eighty-one thousand, six hundred eighty".