661993 has 2 divisors, whose sum is σ = 661994. Its totient is φ = 661992.

The previous prime is 661987. The next prime is 662003. The reversal of 661993 is 399166.

661993 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 can be written as a sum of positive squares in only one way, i.e., 660969 + 1024 = 813^2 + 32^2 .

It is a cyclic number.

It is not a de Polignac number, because 661993 - 2⁵ = 661961 is a prime.

661993 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (661093) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330996 + 330997.

It is an arithmetic number, because the mean of its divisors is an integer number (330997).

2⁶⁶¹⁹⁹³ is an apocalyptic number.

It is an amenable number.

661993 is a deficient number, since it is larger than the sum of its proper divisors (1).

661993 is an equidigital number, since it uses as much as digits as its factorization.

661993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8748, while the sum is 34.

The square root of 661993 is about 813.6295225715. The cubic root of 661993 is about 87.1534263681.

The spelling of 661993 in words is "six hundred sixty-one thousand, nine hundred ninety-three".