661782528 has 288 divisors, whose sum is σ = 2264915520. Its totient is φ = 188743680.

The previous prime is 661782509. The next prime is 661782547. The reversal of 661782528 is 825287166.

661782528 is a `hidden beast` number, since 6 + 617 + 8 + 2 + 5 + 28 = 666.

It is an interprime number because it is at equal distance from previous prime (661782509) and next prime (661782547).

It is a tau number, because it is divible by the number of its divisors (288).

It is a super-2 number, since 2×661782528² = 875912228732141568, which contains 22 as substring.

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, 38928376 + ... + 38928392.

It is an arithmetic number, because the mean of its divisors is an integer number (7864290).

Almost surely, 2^661782528 is an apocalyptic number.

661782528 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 661782528, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1132457760).

661782528 is an abundant number, since it is smaller than the sum of its proper divisors (1603132992).

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

661782528 is an equidigital number, since it uses as much as digits as its factorization.

661782528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71 (or 33 counting only the distinct ones).

The product of its digits is 322560, while the sum is 45.

The square root of 661782528 is about 25725.1341687463. The cubic root of 661782528 is about 871.4418895905.

The spelling of 661782528 in words is "six hundred sixty-one million, seven hundred eighty-two thousand, five hundred twenty-eight".