661281 has 8 divisors (see below), whose sum is σ = 898560. Its totient is φ = 432432.

The previous prime is 661267. The next prime is 661321. The reversal of 661281 is 182166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 661281 - 2⁶ = 661217 is a prime.

It is a super-2 number, since 2×661281² = 874585121922, which contains 22 as substring.

661281 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (661201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1921 + ... + 2238.

It is an arithmetic number, because the mean of its divisors is an integer number (112320).

2⁶⁶¹²⁸¹ is an apocalyptic number.

It is an amenable number.

661281 is a deficient number, since it is larger than the sum of its proper divisors (237279).

661281 is a wasteful number, since it uses less digits than its factorization.

661281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4215.

The product of its digits is 576, while the sum is 24.

The square root of 661281 is about 813.1918592805. The cubic root of 661281 is about 87.1221694918.

The spelling of 661281 in words is "six hundred sixty-one thousand, two hundred eighty-one".