66261660 has 96 divisors (see below), whose sum is σ = 192471552. Its totient is φ = 17022720.

The previous prime is 66261653. The next prime is 66261719. The reversal of 66261660 is 6616266.

It is a congruent number.

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, 212905 + ... + 213215.

It is an arithmetic number, because the mean of its divisors is an integer number (2004912).

Almost surely, 2^66261660 is an apocalyptic number.

66261660 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 66261660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96235776).

66261660 is an abundant number, since it is smaller than the sum of its proper divisors (126209892).

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

66261660 is a wasteful number, since it uses less digits than its factorization.

66261660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 443 (or 441 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 33.

The square root of 66261660 is about 8140.1265346431. The cubic root of 66261660 is about 404.6573538413.

It can be divided in two parts, 66 and 261660, that added together give a triangular number (261726 = T₇₂₃).

The spelling of 66261660 in words is "sixty-six million, two hundred sixty-one thousand, six hundred sixty".