61491191 has 4 divisors (see below), whose sum is σ = 61506984. Its totient is φ = 61475400.

The previous prime is 61491119. The next prime is 61491203. The reversal of 61491191 is 19119416.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61491191 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 (61431191) 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, 2561 + ... + 11381.

It is an arithmetic number, because the mean of its divisors is an integer number (15376746).

Almost surely, 2^61491191 is an apocalyptic number.

61491191 is a deficient number, since it is larger than the sum of its proper divisors (15793).

61491191 is an equidigital number, since it uses as much as digits as its factorization.

61491191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15792.

The product of its digits is 1944, while the sum is 32.

The square root of 61491191 is about 7841.6319092393. The cubic root of 61491191 is about 394.7034916288.

The spelling of 61491191 in words is "sixty-one million, four hundred ninety-one thousand, one hundred ninety-one".