661051 has 4 divisors (see below), whose sum is σ = 664704. Its totient is φ = 657400.

The previous prime is 661049. The next prime is 661061. The reversal of 661051 is 150166.

661051 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 150166 = 2 ⋅75083.

It is a cyclic number.

It is not a de Polignac number, because 661051 - 2¹ = 661049 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1540 + ... + 1921.

It is an arithmetic number, because the mean of its divisors is an integer number (166176).

2⁶⁶¹⁰⁵¹ is an apocalyptic number.

661051 is a deficient number, since it is larger than the sum of its proper divisors (3653).

661051 is a wasteful number, since it uses less digits than its factorization.

661051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3652.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 661051 is about 813.0504289403. The cubic root of 661051 is about 87.1120676730.

The spelling of 661051 in words is "six hundred sixty-one thousand, fifty-one".