61666517 has 4 divisors (see below), whose sum is σ = 67272576. Its totient is φ = 56060460.

The previous prime is 61666487. The next prime is 61666523. The reversal of 61666517 is 71566616.

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.

It is a cyclic number.

It is not a de Polignac number, because 61666517 - 2⁶ = 61666453 is a prime.

It is a super-2 number, since 2×61666517² = 7605518637822578, 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 (61666117) 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, 2803013 + ... + 2803034.

It is an arithmetic number, because the mean of its divisors is an integer number (16818144).

Almost surely, 2^61666517 is an apocalyptic number.

It is an amenable number.

61666517 is a deficient number, since it is larger than the sum of its proper divisors (5606059).

61666517 is a wasteful number, since it uses less digits than its factorization.

61666517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5606058.

The product of its digits is 45360, while the sum is 38.

The square root of 61666517 is about 7852.8031300931. The cubic root of 61666517 is about 395.0782668174.

Subtracting 61666517 from its reverse (71566616), we obtain a palindrome (9900099).

The spelling of 61666517 in words is "sixty-one million, six hundred sixty-six thousand, five hundred seventeen".