661768380 has 360 divisors, whose sum is σ = 2593771488. Its totient is φ = 137541888.

The previous prime is 661768369. The next prime is 661768403. The reversal of 661768380 is 83867166.

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 119 ways as a sum of consecutive naturals, for example, 9877107 + ... + 9877173.

Almost surely, 2^661768380 is an apocalyptic number.

661768380 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 661768380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1296885744).

661768380 is an abundant number, since it is smaller than the sum of its proper divisors (1932003108).

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

661768380 is a wasteful number, since it uses less digits than its factorization.

661768380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175 (or 97 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The square root of 661768380 is about 25724.8591832881. The cubic root of 661768380 is about 871.4356794701.

The spelling of 661768380 in words is "six hundred sixty-one million, seven hundred sixty-eight thousand, three hundred eighty".