665816261040 has 800 divisors, whose sum is σ = 2706769612800. Its totient is φ = 151623166464.

The previous prime is 665816260979. The next prime is 665816261107. The reversal of 665816261040 is 40162618566.

665816261040 is a `hidden beast` number, since 6 + 6 + 5 + 8 + 1 + 626 + 10 + 4 + 0 = 666.

665816261040 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×665816261040² (a number of 24 digits) contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 1029081997 + ... + 1029082643.

It is an arithmetic number, because the mean of its divisors is an integer number (3383462016).

Almost surely, 2^665816261040 is an apocalyptic number.

665816261040 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 665816261040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1353384806400).

665816261040 is an abundant number, since it is smaller than the sum of its proper divisors (2040953351760).

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

665816261040 is a wasteful number, since it uses less digits than its factorization.

665816261040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1156 (or 1127 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 45.

The spelling of 665816261040 in words is "six hundred sixty-five billion, eight hundred sixteen million, two hundred sixty-one thousand, forty".