661471 has 4 divisors (see below), whose sum is σ = 664200. Its totient is φ = 658744.

The previous prime is 661459. The next prime is 661477. The reversal of 661471 is 174166.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 174166 = 2 ⋅87083.

It is a cyclic number.

It is not a de Polignac number, because 661471 - 2⁵ = 661439 is a prime.

It is a super-3 number, since 3×661471³ = 868267771164570333, which contains 333 as substring.

It is a Duffinian number.

661471 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661477) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 961 + ... + 1498.

It is an arithmetic number, because the mean of its divisors is an integer number (166050).

2⁶⁶¹⁴⁷¹ is an apocalyptic number.

661471 is a deficient number, since it is larger than the sum of its proper divisors (2729).

661471 is a wasteful number, since it uses less digits than its factorization.

661471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2728.

The product of its digits is 1008, while the sum is 25.

The square root of 661471 is about 813.3086744896. The cubic root of 661471 is about 87.1305127060.

The spelling of 661471 in words is "six hundred sixty-one thousand, four hundred seventy-one".