6661918445 has 32 divisors (see below), whose sum is σ = 10156554240. Its totient is φ = 4080741120.

The previous prime is 6661918441. The next prime is 6661918457. The reversal of 6661918445 is 5448191666.

It is not a de Polignac number, because 6661918445 - 2² = 6661918441 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6661918393 and 6661918402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6661918441) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 222050 + ... + 250259.

It is an arithmetic number, because the mean of its divisors is an integer number (317392320).

Almost surely, 2^6661918445 is an apocalyptic number.

6661918445 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

6661918445 is a deficient number, since it is larger than the sum of its proper divisors (3494635795).

6661918445 is a wasteful number, since it uses less digits than its factorization.

6661918445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 472365.

The product of its digits is 1244160, while the sum is 50.

The square root of 6661918445 is about 81620.5761128896. The cubic root of 6661918445 is about 1881.6251268728.

The spelling of 6661918445 in words is "six billion, six hundred sixty-one million, nine hundred eighteen thousand, four hundred forty-five".