661739 has 8 divisors (see below), whose sum is σ = 720720. Its totient is φ = 603936.

The previous prime is 661721. The next prime is 661741. The reversal of 661739 is 937166.

661739 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661739 - 2⁸ = 661483 is a prime.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (661769) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1184 + ... + 1650.

It is an arithmetic number, because the mean of its divisors is an integer number (90090).

2⁶⁶¹⁷³⁹ is an apocalyptic number.

661739 is a deficient number, since it is larger than the sum of its proper divisors (58981).

661739 is a wasteful number, since it uses less digits than its factorization.

661739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 589.

The product of its digits is 6804, while the sum is 32.

The square root of 661739 is about 813.4734168982. The cubic root of 661739 is about 87.1422783136.

The spelling of 661739 in words is "six hundred sixty-one thousand, seven hundred thirty-nine".