61661691 has 24 divisors (see below), whose sum is σ = 109622240. Its totient is φ = 32524416.

The previous prime is 61661683. The next prime is 61661723. The reversal of 61661691 is 19616616.

It is not a de Polignac number, because 61661691 - 2³ = 61661683 is a prime.

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 23 ways as a sum of consecutive naturals, for example, 36826 + ... + 38463.

Almost surely, 2^61661691 is an apocalyptic number.

61661691 is a deficient number, since it is larger than the sum of its proper divisors (47960549).

61661691 is a wasteful number, since it uses less digits than its factorization.

61661691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75315 (or 75312 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The square root of 61661691 is about 7852.4958452711. The cubic root of 61661691 is about 395.0679603197.

The spelling of 61661691 in words is "sixty-one million, six hundred sixty-one thousand, six hundred ninety-one".