661099 has 2 divisors, whose sum is σ = 661100. Its totient is φ = 661098.

The previous prime is 661097. The next prime is 661103. The reversal of 661099 is 990166.

661099 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661099 - 2¹ = 661097 is a prime.

Together with 661097, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 661099.

It is not a weakly prime, because it can be changed into another prime (661091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330549 + 330550.

It is an arithmetic number, because the mean of its divisors is an integer number (330550).

2⁶⁶¹⁰⁹⁹ is an apocalyptic number.

661099 is a deficient number, since it is larger than the sum of its proper divisors (1).

661099 is an equidigital number, since it uses as much as digits as its factorization.

661099 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 661099 is about 813.0799468687. The cubic root of 661099 is about 87.1141760721.

The spelling of 661099 in words is "six hundred sixty-one thousand, ninety-nine".