661288 has 16 divisors (see below), whose sum is σ = 1251360. Its totient is φ = 327600.

The previous prime is 661267. The next prime is 661321. The reversal of 661288 is 882166.

661288 is nontrivially palindromic in base 15.

Its product of digits (4608) is a multiple of the sum of its prime factors (768).

It is an unprimeable number.

661288 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 733 + ... + 1363.

It is an arithmetic number, because the mean of its divisors is an integer number (78210).

661288 is a Friedman number, since it can be written as 82661*8, using all its digits and the basic arithmetic operations.

2⁶⁶¹²⁸⁸ is an apocalyptic number.

It is an amenable number.

661288 is a deficient number, since it is larger than the sum of its proper divisors (590072).

661288 is a wasteful number, since it uses less digits than its factorization.

661288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768 (or 764 counting only the distinct ones).

The product of its digits is 4608, while the sum is 31.

The square root of 661288 is about 813.1961632964. The cubic root of 661288 is about 87.1224769018.

It can be divided in two parts, 661 and 288, that added together give a palindrome (949).

The spelling of 661288 in words is "six hundred sixty-one thousand, two hundred eighty-eight".