610991 has 4 divisors (see below), whose sum is σ = 616512. Its totient is φ = 605472.

The previous prime is 610969. The next prime is 610993. The reversal of 610991 is 199016.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-610991 is a prime.

It is a Duffinian number.

It is a plaindrome in base 12.

It is a self number, because there is not a number n which added to its sum of digits gives 610991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (610993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2591 + ... + 2816.

It is an arithmetic number, because the mean of its divisors is an integer number (154128).

2⁶¹⁰⁹⁹¹ is an apocalyptic number.

610991 is a deficient number, since it is larger than the sum of its proper divisors (5521).

610991 is a wasteful number, since it uses less digits than its factorization.

610991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5520.

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 610991 is about 781.6591328706. The cubic root of 610991 is about 84.8551628003.

The spelling of 610991 in words is "six hundred ten thousand, nine hundred ninety-one".