664547421 has 4 divisors (see below), whose sum is σ = 886063232. Its totient is φ = 443031612.

The previous prime is 664547419. The next prime is 664547423. The reversal of 664547421 is 124745466.

664547421 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 an interprime number because it is at equal distance from previous prime (664547419) and next prime (664547423).

It is not a de Polignac number, because 664547421 - 2¹ = 664547419 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 664547421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664547423) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110757901 + ... + 110757906.

It is an arithmetic number, because the mean of its divisors is an integer number (221515808).

Almost surely, 2^664547421 is an apocalyptic number.

It is an amenable number.

664547421 is a deficient number, since it is larger than the sum of its proper divisors (221515811).

664547421 is a wasteful number, since it uses less digits than its factorization.

664547421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221515810.

The product of its digits is 161280, while the sum is 39.

The square root of 664547421 is about 25778.8172924981. The cubic root of 664547421 is about 872.6538163366.

The spelling of 664547421 in words is "six hundred sixty-four million, five hundred forty-seven thousand, four hundred twenty-one".