643477521 has 4 divisors (see below), whose sum is σ = 857970032. Its totient is φ = 428985012.

The previous prime is 643477511. The next prime is 643477529. The reversal of 643477521 is 125774346.

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 643477521 - 2²² = 639283217 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 643477521.

It is not an unprimeable number, because it can be changed into a prime (643477529) 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, 107246251 + ... + 107246256.

It is an arithmetic number, because the mean of its divisors is an integer number (214492508).

Almost surely, 2^643477521 is an apocalyptic number.

It is an amenable number.

643477521 is a deficient number, since it is larger than the sum of its proper divisors (214492511).

643477521 is a wasteful number, since it uses less digits than its factorization.

643477521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214492510.

The product of its digits is 141120, while the sum is 39.

The square root of 643477521 is about 25366.8587136839. The cubic root of 643477521 is about 863.3319099606.

The spelling of 643477521 in words is "six hundred forty-three million, four hundred seventy-seven thousand, five hundred twenty-one".