661410816 has 264 divisors, whose sum is σ = 2064751584. Its totient is φ = 186531840.

The previous prime is 661410773. The next prime is 661410829. The reversal of 661410816 is 618014166.

It is a tau number, because it is divible by the number of its divisors (264).

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17875950 + ... + 17875986.

Almost surely, 2^661410816 is an apocalyptic number.

661410816 is a gapful number since it is divisible by the number (66) 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 661410816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1032375792).

661410816 is an abundant number, since it is smaller than the sum of its proper divisors (1403340768).

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

661410816 is a wasteful number, since it uses less digits than its factorization.

661410816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117 (or 76 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 661410816 is about 25717.9084686139. The cubic root of 661410816 is about 871.2787009998.

The spelling of 661410816 in words is "six hundred sixty-one million, four hundred ten thousand, eight hundred sixteen".