66791261 has 4 divisors (see below), whose sum is σ = 67636800. Its totient is φ = 65945724.

The previous prime is 66791243. The next prime is 66791269. The reversal of 66791261 is 16219766.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 16219766 = 2 ⋅8109883.

It is not a de Polignac number, because 66791261 - 2¹⁸ = 66529117 is a prime.

It is a super-2 number, since 2×66791261² = 8922145091940242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66791269) 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, 422651 + ... + 422808.

It is an arithmetic number, because the mean of its divisors is an integer number (16909200).

Almost surely, 2^66791261 is an apocalyptic number.

It is an amenable number.

66791261 is a deficient number, since it is larger than the sum of its proper divisors (845539).

66791261 is an equidigital number, since it uses as much as digits as its factorization.

66791261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 845538.

The product of its digits is 27216, while the sum is 38.

The square root of 66791261 is about 8172.5920612741. The cubic root of 66791261 is about 405.7325784714.

The spelling of 66791261 in words is "sixty-six million, seven hundred ninety-one thousand, two hundred sixty-one".