61666015 has 4 divisors (see below), whose sum is σ = 73999224. Its totient is φ = 49332808.

The previous prime is 61665991. The next prime is 61666019. The reversal of 61666015 is 51066616.

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

It is a cyclic number.

It is not a de Polignac number, because 61666015 - 2⁹ = 61665503 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 (61666019) 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, 6166597 + ... + 6166606.

It is an arithmetic number, because the mean of its divisors is an integer number (18499806).

Almost surely, 2^61666015 is an apocalyptic number.

61666015 is a deficient number, since it is larger than the sum of its proper divisors (12333209).

61666015 is a wasteful number, since it uses less digits than its factorization.

61666015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12333208.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 61666015 is about 7852.7711669194. The cubic root of 61666015 is about 395.0771947617.

The spelling of 61666015 in words is "sixty-one million, six hundred sixty-six thousand, fifteen".