661057 has 4 divisors (see below), whose sum is σ = 671956. Its totient is φ = 650160.

The previous prime is 661049. The next prime is 661061. The reversal of 661057 is 750166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 750166 = 2 ⋅375083.

It can be written as a sum of positive squares in 2 ways, for example, as 69696 + 591361 = 264^2 + 769^2 .

It is a cyclic number.

It is not a de Polignac number, because 661057 - 2³ = 661049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661027) by changing a digit.

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, 5358 + ... + 5479.

It is an arithmetic number, because the mean of its divisors is an integer number (167989).

2⁶⁶¹⁰⁵⁷ is an apocalyptic number.

It is an amenable number.

661057 is a deficient number, since it is larger than the sum of its proper divisors (10899).

661057 is a wasteful number, since it uses less digits than its factorization.

661057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10898.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 661057 is about 813.0541187400. The cubic root of 661057 is about 87.1123312285.

The spelling of 661057 in words is "six hundred sixty-one thousand, fifty-seven".