61666605 has 144 divisors (see below), whose sum is σ = 147498624. Its totient is φ = 23016960.

The previous prime is 61666589. The next prime is 61666639. The reversal of 61666605 is 50666616.

It is not a de Polignac number, because 61666605 - 2⁴ = 61666589 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 61666605.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 1666647 + ... + 1666683.

It is an arithmetic number, because the mean of its divisors is an integer number (1024296).

Almost surely, 2^61666605 is an apocalyptic number.

61666605 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

61666605 is an abundant number, since it is smaller than the sum of its proper divisors (85832019).

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

61666605 is a wasteful number, since it uses less digits than its factorization.

61666605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116 (or 76 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 36.

The square root of 61666605 is about 7852.8087331859. The cubic root of 61666605 is about 395.0784547469.

It can be divided in two parts, 61 and 666605, that added together give a palindrome (666666).

The spelling of 61666605 in words is "sixty-one million, six hundred sixty-six thousand, six hundred five".