643769520 has 40 divisors (see below), whose sum is σ = 1995686256. Its totient is φ = 171671808.

The previous prime is 643769507. The next prime is 643769527. The reversal of 643769520 is 25967346.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (643769527) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1340947 + ... + 1341426.

Almost surely, 2^643769520 is an apocalyptic number.

643769520 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

643769520 is an abundant number, since it is smaller than the sum of its proper divisors (1351916736).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

643769520 is a wasteful number, since it uses less digits than its factorization.

643769520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2682389 (or 2682383 counting only the distinct ones).

The product of its (nonzero) digits is 272160, while the sum is 42.

The square root of 643769520 is about 25372.6135823647. The cubic root of 643769520 is about 863.4624785891.

It can be divided in two parts, 6437 and 69520, that added together give a palindrome (75957).

The spelling of 643769520 in words is "six hundred forty-three million, seven hundred sixty-nine thousand, five hundred twenty".