6656756921 has 8 divisors (see below), whose sum is σ = 6691356000. Its totient is φ = 6622187040.

The previous prime is 6656756917. The next prime is 6656756957. The reversal of 6656756921 is 1296576566.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6656756921 - 2² = 6656756917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6656756021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 563645 + ... + 575333.

It is an arithmetic number, because the mean of its divisors is an integer number (836419500).

Almost surely, 2^6656756921 is an apocalyptic number.

It is an amenable number.

6656756921 is a deficient number, since it is larger than the sum of its proper divisors (34599079).

6656756921 is a wasteful number, since it uses less digits than its factorization.

6656756921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14599.

The product of its digits is 4082400, while the sum is 53.

The square root of 6656756921 is about 81588.9509737685. The cubic root of 6656756921 is about 1881.1390525461.

The spelling of 6656756921 in words is "six billion, six hundred fifty-six million, seven hundred fifty-six thousand, nine hundred twenty-one".