66028261 has 4 divisors (see below), whose sum is σ = 71107372. Its totient is φ = 60949152.

The previous prime is 66028241. The next prime is 66028271. The reversal of 66028261 is 16282066.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2825761 + 63202500 = 1681^2 + 7950^2 .

It is a cyclic number.

It is not a de Polignac number, because 66028261 - 2⁵ = 66028229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66028241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2539536 + ... + 2539561.

It is an arithmetic number, because the mean of its divisors is an integer number (17776843).

Almost surely, 2^66028261 is an apocalyptic number.

It is an amenable number.

66028261 is a deficient number, since it is larger than the sum of its proper divisors (5079111).

66028261 is a wasteful number, since it uses less digits than its factorization.

66028261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5079110.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 66028261 is about 8125.7775627936. Note that the first 3 decimals coincide. The cubic root of 66028261 is about 404.1816753888.

The spelling of 66028261 in words is "sixty-six million, twenty-eight thousand, two hundred sixty-one".