661628 has 18 divisors (see below), whose sum is σ = 1273608. Its totient is φ = 300520.

The previous prime is 661621. The next prime is 661663. The reversal of 661628 is 826166.

It is a super-2 number, since 2×661628² = 875503220768, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 661628.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661621) by changing a digit.

661628 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 5 ways as a sum of consecutive naturals, for example, 200 + ... + 1167.

It is an arithmetic number, because the mean of its divisors is an integer number (70756).

2⁶⁶¹⁶²⁸ is an apocalyptic number.

It is an amenable number.

661628 is a deficient number, since it is larger than the sum of its proper divisors (611980).

661628 is a wasteful number, since it uses less digits than its factorization.

661628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1393 (or 1380 counting only the distinct ones).

The product of its digits is 3456, while the sum is 29.

The square root of 661628 is about 813.4051880828. The cubic root of 661628 is about 87.1374056302.

The spelling of 661628 in words is "six hundred sixty-one thousand, six hundred twenty-eight".