661072 has 20 divisors (see below), whose sum is σ = 1299520. Its totient is φ = 325728.

The previous prime is 661061. The next prime is 661091. The reversal of 661072 is 270166.

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1003 + ... + 1525.

It is an arithmetic number, because the mean of its divisors is an integer number (64976).

2⁶⁶¹⁰⁷² is an apocalyptic number.

It is an amenable number.

661072 is a deficient number, since it is larger than the sum of its proper divisors (638448).

661072 is a wasteful number, since it uses less digits than its factorization.

661072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 610 (or 604 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 661072 is about 813.0633431658. The cubic root of 661072 is about 87.1129901102.

The spelling of 661072 in words is "six hundred sixty-one thousand, seventy-two".