661653828 has 144 divisors (see below), whose sum is σ = 1876597632. Its totient is φ = 194880000.

The previous prime is 661653809. The next prime is 661653841. The reversal of 661653828 is 828356166.

661653828 is a `hidden beast` number, since 6 + 616 + 5 + 3 + 8 + 28 = 666.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 2839600 + ... + 2839832.

It is an arithmetic number, because the mean of its divisors is an integer number (13031928).

Almost surely, 2^661653828 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661653828, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (938298816).

661653828 is an abundant number, since it is smaller than the sum of its proper divisors (1214943804).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661653828 is a wasteful number, since it uses less digits than its factorization.

661653828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 426 (or 421 counting only the distinct ones).

The product of its digits is 414720, while the sum is 45.

The square root of 661653828 is about 25722.6326024379. The cubic root of 661653828 is about 871.3853947766.

The spelling of 661653828 in words is "six hundred sixty-one million, six hundred fifty-three thousand, eight hundred twenty-eight".