661151 has 4 divisors (see below), whose sum is σ = 669600. Its totient is φ = 652704.

The previous prime is 661139. The next prime is 661183. The reversal of 661151 is 151166.

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: 151166 = 2 ⋅75583.

It is a cyclic number.

It is not a de Polignac number, because 661151 - 2¹⁴ = 644767 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 (661121) 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 3 ways as a sum of consecutive naturals, for example, 4106 + ... + 4263.

It is an arithmetic number, because the mean of its divisors is an integer number (167400).

2⁶⁶¹¹⁵¹ is an apocalyptic number.

661151 is a deficient number, since it is larger than the sum of its proper divisors (8449).

661151 is an equidigital number, since it uses as much as digits as its factorization.

661151 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8448.

The product of its digits is 180, while the sum is 20.

The square root of 661151 is about 813.1119234152. Note that the first 3 decimals coincide. The cubic root of 661151 is about 87.1164600560.

The spelling of 661151 in words is "six hundred sixty-one thousand, one hundred fifty-one".