656209921 has 8 divisors (see below), whose sum is σ = 671423904. Its totient is φ = 641164320.

The previous prime is 656209919. The next prime is 656209927. The reversal of 656209921 is 129902656.

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 656209921 - 2¹ = 656209919 is a prime.

It is a super-2 number, since 2×656209921² = 861222920837652482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (656209927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34195 + ... + 49816.

It is an arithmetic number, because the mean of its divisors is an integer number (83927988).

Almost surely, 2^656209921 is an apocalyptic number.

It is an amenable number.

656209921 is a deficient number, since it is larger than the sum of its proper divisors (15213983).

656209921 is a wasteful number, since it uses less digits than its factorization.

656209921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84191.

The product of its (nonzero) digits is 58320, while the sum is 40.

The square root of 656209921 is about 25616.5946409744. The cubic root of 656209921 is about 868.9889699825.

The spelling of 656209921 in words is "six hundred fifty-six million, two hundred nine thousand, nine hundred twenty-one".