66771840 has 128 divisors (see below), whose sum is σ = 215913600. Its totient is φ = 17549312.

The previous prime is 66771839. The next prime is 66771851. The reversal of 66771840 is 4817766.

66771840 is nontrivially palindromic in base 11.

It is a tau number, because it is divible by the number of its divisors (128).

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, 159151 + ... + 159569.

It is an arithmetic number, because the mean of its divisors is an integer number (1686825).

Almost surely, 2^66771840 is an apocalyptic number.

66771840 is a gapful number since it is divisible by the number (60) 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 66771840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (107956800).

66771840 is an abundant number, since it is smaller than the sum of its proper divisors (149141760).

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

66771840 is a wasteful number, since it uses less digits than its factorization.

66771840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 524 (or 512 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 39.

The square root of 66771840 is about 8171.4037961662. The cubic root of 66771840 is about 405.6932494926.

The spelling of 66771840 in words is "sixty-six million, seven hundred seventy-one thousand, eight hundred forty".