66428240 has 20 divisors (see below), whose sum is σ = 154445844. Its totient is φ = 26571264.

The previous prime is 66428233. The next prime is 66428251. The reversal of 66428240 is 4282466.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17372224 + 49056016 = 4168^2 + 7004^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×66428240² = 8825422138995200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 66428197 and 66428206.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 415097 + ... + 415256.

Almost surely, 2^66428240 is an apocalyptic number.

It is an amenable number.

66428240 is an abundant number, since it is smaller than the sum of its proper divisors (88017604).

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

66428240 is a wasteful number, since it uses less digits than its factorization.

66428240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 830366 (or 830360 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 32.

The square root of 66428240 is about 8150.3521396318. The cubic root of 66428240 is about 404.9961692469.

It can be divided in two parts, 6 and 6428240, that added together give a palindrome (6428246).

The spelling of 66428240 in words is "sixty-six million, four hundred twenty-eight thousand, two hundred forty".