66641718 has 96 divisors (see below), whose sum is σ = 165166848. Its totient is φ = 17772480.

The previous prime is 66641713. The next prime is 66641737. The reversal of 66641718 is 81714666.

It is a happy number.

It is a super-2 number, since 2×66641718² = 8882237155983048, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66641711) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 216921 + ... + 217227.

It is an arithmetic number, because the mean of its divisors is an integer number (1720488).

Almost surely, 2^66641718 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66641718, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (82583424).

66641718 is an abundant number, since it is smaller than the sum of its proper divisors (98525130).

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

66641718 is a wasteful number, since it uses less digits than its factorization.

66641718 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 370 (or 359 counting only the distinct ones).

The product of its digits is 48384, while the sum is 39.

The square root of 66641718 is about 8163.4378787371. The cubic root of 66641718 is about 405.4295457839.

It can be divided in two parts, 666417 and 18, that added together give a triangular number (666435 = T₁₁₅₄).

The spelling of 66641718 in words is "sixty-six million, six hundred forty-one thousand, seven hundred eighteen".