64197921 has 4 divisors (see below), whose sum is σ = 85597232. Its totient is φ = 42798612.

The previous prime is 64197907. The next prime is 64197929. The reversal of 64197921 is 12979146.

64197921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 64197921 - 2¹³ = 64189729 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 64197921.

It is not an unprimeable number, because it can be changed into a prime (64197929) 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 3 ways as a sum of consecutive naturals, for example, 10699651 + ... + 10699656.

It is an arithmetic number, because the mean of its divisors is an integer number (21399308).

Almost surely, 2^64197921 is an apocalyptic number.

It is an amenable number.

64197921 is a deficient number, since it is larger than the sum of its proper divisors (21399311).

64197921 is a wasteful number, since it uses less digits than its factorization.

64197921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21399310.

The product of its digits is 27216, while the sum is 39.

The square root of 64197921 is about 8012.3605136065. The cubic root of 64197921 is about 400.4119110942.

The spelling of 64197921 in words is "sixty-four million, one hundred ninety-seven thousand, nine hundred twenty-one".