61661687 has 4 divisors (see below), whose sum is σ = 61836720. Its totient is φ = 61486656.

The previous prime is 61661683. The next prime is 61661723. The reversal of 61661687 is 78616616.

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 61661687 - 2² = 61661683 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 (61661681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86987 + ... + 87692.

It is an arithmetic number, because the mean of its divisors is an integer number (15459180).

Almost surely, 2^61661687 is an apocalyptic number.

61661687 is a deficient number, since it is larger than the sum of its proper divisors (175033).

61661687 is a wasteful number, since it uses less digits than its factorization.

61661687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175032.

The product of its digits is 72576, while the sum is 41.

The square root of 61661687 is about 7852.4955905750. The cubic root of 61661687 is about 395.0679517770.

The spelling of 61661687 in words is "sixty-one million, six hundred sixty-one thousand, six hundred eighty-seven".