61686691 has 4 divisors (see below), whose sum is σ = 67294584. Its totient is φ = 56078800.

The previous prime is 61686661. The next prime is 61686707. The reversal of 61686691 is 19668616.

It is a happy number.

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 61686691 - 2¹⁵ = 61653923 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61686631) 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, 2803930 + ... + 2803951.

It is an arithmetic number, because the mean of its divisors is an integer number (16823646).

Almost surely, 2^61686691 is an apocalyptic number.

61686691 is a deficient number, since it is larger than the sum of its proper divisors (5607893).

61686691 is a wasteful number, since it uses less digits than its factorization.

61686691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5607892.

The product of its digits is 93312, while the sum is 43.

The square root of 61686691 is about 7854.0875345262. The cubic root of 61686691 is about 395.1213449758.

The spelling of 61686691 in words is "sixty-one million, six hundred eighty-six thousand, six hundred ninety-one".