661676400 has 810 divisors, whose sum is σ = 3030701856. Its totient is φ = 133056000.

The previous prime is 661676371. The next prime is 661676401. The reversal of 661676400 is 4676166.

661676400 is a `hidden beast` number, since 6 + 6 + 1 + 6 + 7 + 640 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661676401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 161 ways as a sum of consecutive naturals, for example, 21344385 + ... + 21344415.

Almost surely, 2^661676400 is an apocalyptic number.

661676400 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 661676400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1515350928).

661676400 is an abundant number, since it is smaller than the sum of its proper divisors (2369025456).

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

661676400 is a wasteful number, since it uses less digits than its factorization.

661676400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91 (or 59 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

The square root of 661676400 is about 25723.0713562747. The cubic root of 661676400 is about 871.3953036275.

The spelling of 661676400 in words is "six hundred sixty-one million, six hundred seventy-six thousand, four hundred".