66695921 has 4 divisors (see below), whose sum is σ = 66715200. Its totient is φ = 66676644.

The previous prime is 66695917. The next prime is 66695927. The reversal of 66695921 is 12959666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66695921 - 2² = 66695917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66695927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2861 + ... + 11898.

It is an arithmetic number, because the mean of its divisors is an integer number (16678800).

Almost surely, 2^66695921 is an apocalyptic number.

It is an amenable number.

66695921 is a deficient number, since it is larger than the sum of its proper divisors (19279).

66695921 is a wasteful number, since it uses less digits than its factorization.

66695921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19278.

The product of its digits is 174960, while the sum is 44.

The square root of 66695921 is about 8166.7570675269. The cubic root of 66695921 is about 405.5394346198.

The spelling of 66695921 in words is "sixty-six million, six hundred ninety-five thousand, nine hundred twenty-one".