661481 has 2 divisors, whose sum is σ = 661482. Its totient is φ = 661480.

The previous prime is 661477. The next prime is 661483. The reversal of 661481 is 184166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 648025 + 13456 = 805^2 + 116^2 .

It is a cyclic number.

It is not a de Polignac number, because 661481 - 2² = 661477 is a prime.

It is a super-2 number, since 2×661481² = 875114226722, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 661483, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 661481.

It is not a weakly prime, because it can be changed into another prime (661483) 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 as a sum of consecutive naturals, namely, 330740 + 330741.

It is an arithmetic number, because the mean of its divisors is an integer number (330741).

2⁶⁶¹⁴⁸¹ is an apocalyptic number.

It is an amenable number.

661481 is a deficient number, since it is larger than the sum of its proper divisors (1).

661481 is an equidigital number, since it uses as much as digits as its factorization.

661481 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 26.

The square root of 661481 is about 813.3148221937. The cubic root of 661481 is about 87.1309517783.

The spelling of 661481 in words is "six hundred sixty-one thousand, four hundred eighty-one".