661995 has 24 divisors (see below), whose sum is σ = 1175616. Its totient is φ = 344448.

The previous prime is 661993. The next prime is 662003. The reversal of 661995 is 599166.

It is not a de Polignac number, because 661995 - 2¹ = 661993 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 661995.

It is not an unprimeable number, because it can be changed into a prime (661993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1959 + ... + 2271.

It is an arithmetic number, because the mean of its divisors is an integer number (48984).

2⁶⁶¹⁹⁹⁵ is an apocalyptic number.

661995 is a deficient number, since it is larger than the sum of its proper divisors (513621).

661995 is a wasteful number, since it uses less digits than its factorization.

661995 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 371 (or 368 counting only the distinct ones).

The product of its digits is 14580, while the sum is 36.

The square root of 661995 is about 813.6307516312. The cubic root of 661995 is about 87.1535141367.

It can be divided in two parts, 6 and 61995, that added together give a square (62001 = 249²).

The spelling of 661995 in words is "six hundred sixty-one thousand, nine hundred ninety-five".