643825481 has 4 divisors (see below), whose sum is σ = 693350532. Its totient is φ = 594300432.

The previous prime is 643825459. The next prime is 643825517. The reversal of 643825481 is 184528346.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 264355081 + 379470400 = 16259^2 + 19480^2 .

It is a cyclic number.

It is not a de Polignac number, because 643825481 - 2⁶ = 643825417 is a prime.

It is a super-2 number, since 2×643825481² = 829022499969762722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643822481) 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, 24762506 + ... + 24762531.

It is an arithmetic number, because the mean of its divisors is an integer number (173337633).

Almost surely, 2^643825481 is an apocalyptic number.

It is an amenable number.

643825481 is a deficient number, since it is larger than the sum of its proper divisors (49525051).

643825481 is a wasteful number, since it uses less digits than its factorization.

643825481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49525050.

The product of its digits is 184320, while the sum is 41.

The square root of 643825481 is about 25373.7163419157. The cubic root of 643825481 is about 863.4874972862.

The spelling of 643825481 in words is "six hundred forty-three million, eight hundred twenty-five thousand, four hundred eighty-one".