661826880 has 336 divisors, whose sum is σ = 2676046464. Its totient is φ = 148008960.

The previous prime is 661826857. The next prime is 661826923. The reversal of 661826880 is 88628166.

661826880 is a `hidden beast` number, since 6 + 618 + 26 + 8 + 8 + 0 = 666.

It is a super-3 number, since 3×661826880³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 411037 + ... + 412643.

It is an arithmetic number, because the mean of its divisors is an integer number (7964424).

Almost surely, 2^661826880 is an apocalyptic number.

661826880 is a gapful number since it is divisible by the number (60) 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 661826880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1338023232).

661826880 is an abundant number, since it is smaller than the sum of its proper divisors (2014219584).

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

661826880 is a wasteful number, since it uses less digits than its factorization.

661826880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1654 (or 1641 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 45.

The square root of 661826880 is about 25725.9961906240. The cubic root of 661826880 is about 871.4613568756.

It can be divided in two parts, 661 and 826880, that added together give a triangular number (827541 = T₁₂₈₆).

The spelling of 661826880 in words is "six hundred sixty-one million, eight hundred twenty-six thousand, eight hundred eighty".