661556016 has 60 divisors (see below), whose sum is σ = 2019755400. Its totient is φ = 200471040.

The previous prime is 661556011. The next prime is 661556047. The reversal of 661556016 is 610655166.

661556016 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not an unprimeable number, because it can be changed into a prime (661556011) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 207241 + ... + 210408.

It is an arithmetic number, because the mean of its divisors is an integer number (33662590).

Almost surely, 2^661556016 is an apocalyptic number.

661556016 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

661556016 is an abundant number, since it is smaller than the sum of its proper divisors (1358199384).

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

661556016 is a wasteful number, since it uses less digits than its factorization.

661556016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 417674 (or 417665 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 36.

The square root of 661556016 is about 25720.7312493249. The cubic root of 661556016 is about 871.3424538182.

The spelling of 661556016 in words is "six hundred sixty-one million, five hundred fifty-six thousand, sixteen".