6665521655 has 16 divisors (see below), whose sum is σ = 8616558720. Its totient is φ = 4920715008.

The previous prime is 6665521609. The next prime is 6665521663. The reversal of 6665521655 is 5561255666.

It is a cyclic number.

It is not a de Polignac number, because 6665521655 - 2⁶ = 6665521591 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 224786 + ... + 252704.

It is an arithmetic number, because the mean of its divisors is an integer number (538534920).

Almost surely, 2^6665521655 is an apocalyptic number.

6665521655 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

6665521655 is a deficient number, since it is larger than the sum of its proper divisors (1951037065).

6665521655 is a wasteful number, since it uses less digits than its factorization.

6665521655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31610.

The product of its digits is 1620000, while the sum is 47.

The square root of 6665521655 is about 81642.6460558451. The cubic root of 6665521655 is about 1881.9643018696.

The spelling of 6665521655 in words is "six billion, six hundred sixty-five million, five hundred twenty-one thousand, six hundred fifty-five".