61709991 has 8 divisors (see below), whose sum is σ = 94034304. Its totient is φ = 35262840.

The previous prime is 61709987. The next prime is 61710001. The reversal of 61709991 is 19990716.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 61709991 - 2² = 61709987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61709971) 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 7 ways as a sum of consecutive naturals, for example, 1469265 + ... + 1469306.

It is an arithmetic number, because the mean of its divisors is an integer number (11754288).

Almost surely, 2^61709991 is an apocalyptic number.

61709991 is a deficient number, since it is larger than the sum of its proper divisors (32324313).

61709991 is a wasteful number, since it uses less digits than its factorization.

61709991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2938581.

The product of its (nonzero) digits is 30618, while the sum is 42.

The square root of 61709991 is about 7855.5706985553. The cubic root of 61709991 is about 395.1710864912.

It can be divided in two parts, 6170 and 9991, that added together give a palindrome (16161).

The spelling of 61709991 in words is "sixty-one million, seven hundred nine thousand, nine hundred ninety-one".