661018208 has 96 divisors (see below), whose sum is σ = 1497968640. Its totient is φ = 285050880.

The previous prime is 661018153. The next prime is 661018213. The reversal of 661018208 is 802810166.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 319385 + ... + 321447.

It is an arithmetic number, because the mean of its divisors is an integer number (15603840).

Almost surely, 2^661018208 is an apocalyptic number.

661018208 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661018208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (748984320).

661018208 is an abundant number, since it is smaller than the sum of its proper divisors (836950432).

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

661018208 is a wasteful number, since it uses less digits than its factorization.

661018208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2140 (or 2132 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 661018208 is about 25710.2743664863. The cubic root of 661018208 is about 871.1062722632.

The spelling of 661018208 in words is "six hundred sixty-one million, eighteen thousand, two hundred eight".