661673 has 2 divisors, whose sum is σ = 661674. Its totient is φ = 661672.

The previous prime is 661663. The next prime is 661679. The reversal of 661673 is 376166.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 394384 + 267289 = 628^2 + 517^2 .

It is a cyclic number.

It is not a de Polignac number, because 661673 - 2⁸ = 661417 is a prime.

It is a super-2 number, since 2×661673² = 875622317858, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (661679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330836 + 330837.

It is an arithmetic number, because the mean of its divisors is an integer number (330837).

2⁶⁶¹⁶⁷³ is an apocalyptic number.

It is an amenable number.

661673 is a deficient number, since it is larger than the sum of its proper divisors (1).

661673 is an equidigital number, since it uses as much as digits as its factorization.

661673 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4536, while the sum is 29.

The square root of 661673 is about 813.4328491031. The cubic root of 661673 is about 87.1393811081.

The spelling of 661673 in words is "six hundred sixty-one thousand, six hundred seventy-three".