661535 has 16 divisors (see below), whose sum is σ = 931392. Its totient is φ = 441600.

The previous prime is 661517. The next prime is 661541. The reversal of 661535 is 535166.

It is not a de Polignac number, because 661535 - 2¹² = 657439 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1205 + ... + 1665.

It is an arithmetic number, because the mean of its divisors is an integer number (58212).

2⁶⁶¹⁵³⁵ is an apocalyptic number.

661535 is a deficient number, since it is larger than the sum of its proper divisors (269857).

661535 is a wasteful number, since it uses less digits than its factorization.

661535 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 514.

The product of its digits is 2700, while the sum is 26.

The square root of 661535 is about 813.3480189931. The cubic root of 661535 is about 87.1333226922.

The spelling of 661535 in words is "six hundred sixty-one thousand, five hundred thirty-five".