61666405 has 8 divisors (see below), whose sum is σ = 74050200. Its totient is φ = 49299456.

The previous prime is 61666403. The next prime is 61666417. The reversal of 61666405 is 50466616.

It can be written as a sum of positive squares in 4 ways, for example, as 294849 + 61371556 = 543^2 + 7834^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 61666405 - 2¹ = 61666403 is a prime.

It is a super-3 number, since 3×61666405³ (a number of 24 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61666403) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6181 + ... + 12709.

It is an arithmetic number, because the mean of its divisors is an integer number (9256275).

Almost surely, 2^61666405 is an apocalyptic number.

It is an amenable number.

61666405 is a deficient number, since it is larger than the sum of its proper divisors (12383795).

61666405 is a wasteful number, since it uses less digits than its factorization.

61666405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8423.

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 61666405 is about 7852.7959988784. The cubic root of 61666405 is about 395.0780276342.

The spelling of 61666405 in words is "sixty-one million, six hundred sixty-six thousand, four hundred five".