61115991 has 16 divisors (see below), whose sum is σ = 85349376. Its totient is φ = 38826656.

The previous prime is 61115987. The next prime is 61116001. The reversal of 61115991 is 19951116.

It is a cyclic number.

It is not a de Polignac number, because 61115991 - 2² = 61115987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61115921) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18706 + ... + 21728.

It is an arithmetic number, because the mean of its divisors is an integer number (5334336).

Almost surely, 2^61115991 is an apocalyptic number.

61115991 is a deficient number, since it is larger than the sum of its proper divisors (24233385).

61115991 is a wasteful number, since it uses less digits than its factorization.

61115991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3342.

The product of its digits is 2430, while the sum is 33.

The square root of 61115991 is about 7817.6717122171. The cubic root of 61115991 is about 393.8990675693.

The spelling of 61115991 in words is "sixty-one million, one hundred fifteen thousand, nine hundred ninety-one".